Abstract:     The evaluation of Science and Technology (S&T) plays a key role in the construction of S&T environment in China. As an institutional document of S&T evaluation activities, S&T evaluation policies at the national level directly guide the practical evaluation and affect the evaluation effectiveness. Taking 484 China′s S&T evaluation policies from 1978 to 2018 as the research samples, this study analyzes and summarizes the changes and evolutions of its basic characteristics, policy subjects and collaborative networks through systematic text mining and network analysis. On the whole, the number of S&T evaluation policies in China shows a steady rising trend. After 2016, the number of policies showed the stage characteristics of "blowout" growth. Projects, organizations, personnel and funds are the top four evaluation objects. Pre-evaluation and post evaluation are the most frequently used evaluation methods. Therefore, S&T evaluation in China since the reform and opening up could be divided into four stages: the recovery and reconstruction period (1978-1984), the exploration period (1985-1997), the development period (1998-2011) and the improvement period (2012 to now). It also founds that with the deepening of the development of evaluation activities, the subjects of S&T evaluation policy show a diversified development trend, which basically covers all elements of S&T activities. However, the current S&T evaluation policies mainly focus on organization, personnel and project evaluation, and pay less attention on evaluation of S&T planning, policy and development field. The content of evaluation policy has gradually improved and enriched from the initial evaluation methods, modes and application of evaluation results to each link of the evaluation activity chain, including evaluation methods, modes, procedures, indicators, application of evaluation results, classified evaluation and constructive clauses. Among them, constructive clauses and classified evaluation have existed in different development periods of S&T evaluation since the 1980s and 1990s, and are still the high-frequency content of S&T evaluation policies so far. This shows that despite the frequent occurrence of policies, there are still some problems in policy documents, such as too many guiding and normative opinions and insufficient practical contents. The number of nodes in the collaborative networks has increased as well as the frequency of cooperation. However, the proportion of jointly issued policies in the total number of policies is not high. In most cases, each department still adopts self-made rules, which is easy to cause "fragmentation" management dilemma. In general, China′s S&T evaluation policies have formed a relatively complete evaluation system after long-term development. In the future, the government should rationally allocate policy attention and increase the evaluation of macro-objects, for example, S&T planning and policy. The executable policy documents should be restrengthened, so as to avoid the deviation of policy implementation. The government should also strengthen the coordination of institutions in order to reduce the transaction cost etc.

Key words: science and technology evaluation policy, policy evolution, basic characteristics, policy subject, collaborative network