Abstract: The era of digital economy has arrived. Big data has become a new driving force for economic transformation and development, and it is also the key to promoting high-quality economic and social development. In the context of global integration and rapid digital development, the ability of a country to master and use big data will become an important manifestation of national competitiveness. Big data development has been put on the global agenda. The major countries in the world have successively released big data strategies. Organizations such as the United Nations, the World Bank, and the World Economic Forum etc. have also released reports to actively explore the relationship between big data and economic and social development. Therefore, it is becoming more and more urgent to develop a scientific and reasonable big data policy system to support the high-quality development of big data. The relevant research on big data policy in the academic world mainly focuses on the comparative research on the spatial dimension, lacking of systematic analysis on big data policy of its evolution, policy networks, the evolution of policy thematic word, and the use of policy instruments.Based on this, this paper will start from the two dimensions of policy instrument and policy thematic word, make a textual quantitative analysis of those policies from four aspects by constructing " Policy Instrument -- Policy Thematic Word " two-dimensional analytical framework. The four aspects are as follows: the evolution of China's big data policies, policy networks of big data policies, the evolution of policy thematic words, and the use of policy instruments. The big data policy texts selected in this paper are all from public data sources, mainly collected from the websites of the Chinese government and the ministries and commissions. In order to reflect the status quo of China's big data policy more comprehensively, the original policy texts are obtained by searching for keywords such as “big data”, “artificial intelligence”, “informatization” and “cloud computing” and so on. On that basis, a total of 94 policy texts related to big data were selected as the analysis objects. This paper regards 2000 as the start of China's big data policy research. The reason is that the bursting of the tech and telecom bubble in 2000, which threatened to pull the economy into recession. In order to help the software and the integrated circuit industries, the State Planning Commission (now renamed the National Development and Reform Commission) and other 13 ministries and commissions jointly issued a policy < Several Policies for Encouraging the Development of Software Industry and Integrated Circuit Industry>, to support the development of the software industry and integrated circuit industry. It is a crucial time for the rapid development of the information industry.The research results show that the development of big data policy in China has experienced a development process from emphasizing infrastructure construction to focus on industrial cultivation and innovation, and then to build a big data policy system. In the first stage of thedevelopment process of the big data policy system, the government mainly focuses on the infrastructure construction related to big data. In the second stage, the government focuses on promoting the research and development and demonstration and application projects of the Internet of Things, Cloud Computing, Big Data, the Chinese government is also putting an intensive focus on strategic emerging industries. The third stage of the development process is the construction stage of China's big data policy system. The Chinese government takes the development of the big data as its national strategy to promote the development of big data. At different stages of the development process of big data policy, policy themes are closely related to the economic, social and international environment at that time. In the early stage, China's big data policy theme focuses on the construction of infrastructure, in order to help the software and the integrated circuit industries, the Chinese government issued special policies, developing the information industry in an effort to accelerate nationalinformatization processes. Since 2010, the Chinese government stressed the importance for the country to accelerate the cultivation and development of strategic emerging industries, " cloud computing " and " strategic emerging industries " are representative policy thematic words. In recent years, China's big data policy thematic words focus on big data technology and application, such as "Internet +" "Artificial Intelligence" "cloud platform” etc. Based on existing research results,and in combination with the connotation and development characteristics of big data, this paper classifies policy instruments into ten types. They are talent policy, market-access policy, fiscal policy, tax policy, financial policy, government procurement, international development, intellectual property protection, infrastructure construction, and innovative service platform. Through the statistical analysis we found that the most used is market-access policy instrument (25.00%)，followed by the infrastructure construction (22.18%). The financial policy instrument (9.51%) and fiscal policy instrument (9.15%) are also used more, and this shows that the development of China's big data as a whole is still in the initial stage of the development process, the state attaches great importance to the construction of infrastructure and platforms, is accompanied by the capital investment in the development of big data. However, intellectual property protection (3.70%) and government procurement policy instrument (2.11%) are used less frequently than other policy instruments. International development (6.51%) is used more frequently. Under the guidance of the principles of innovative, coordinated, green, open, and shared development, we should endeavor to bolster international exchanges and cooperation. At present, China has initially established a big data policy network system, which has formed a pattern of coexistence of large and small networks. The development and application of big data are changing with each passing day. China's big data is still in the initial stage of the development process. The big data policy system with perfect system and organic synergy has not yet been established. The top-level design of big data policy is still not perfect, and we still need to further improve and strengthen it.

Key words: big data policy, evolutionary context, policy network, policy instruments, policy documents quantitative analysis