Abstract:     Over the past 40 years of reform and opening-up, China′s economy has maintained rapid growth, and has made a great achievement that amazed the world. In 2010, it became the world′s second largest economy. However, extensive economic growth has led to increasingly serious problems such as waste of resources and environmental pollution, which have seriously affected the sustainable and green development of the economy. It urgently needs to transform economic development model that relies on the input of a large amount of labor, energy, and other traditional factors, and transform to a total factor productivity (TFP) growth model that relies on technological progress, innovate economic development methods, and achieving high-quality economic development. Foreign Direct Investment (FDI) is an important driving force for achieving high-quality economic development in China. We must always attach great importance to the use of foreign capital in the process of promoting high-quality economic development and modernization. Technological innovation capability is the most critical manifestation for a country′s strength, which depends not only on independent R&D, but also on international technology spillover such as FDI. FDI is an important way to take advantage of late-comer advantages and accelerate innovation and development. At present, China′s economy has shifted from a stage of high growth to high-quality development. In the process of "higher level of opening to the outside world", how to attract and make use of FDI at a higher level, especially with high-quality, to promote innovative development, which is a practical problem that needs to be resolved urgently. Based on the above realistic background, this paper fully draws on the existing literature and explores the ways and mechanisms of FDI affecting high-quality economic development. The paper uses the panel data of 30 provincial-level regions in China from 2003 to 2017 to conduct an empirical analysis of theoretical expectations by using the instrumental variable (IV-2SLS), intermediary effects and threshold models. The research found that: under the constraints of environmental regulations, there is a significant role in promoting technological innovation, and "Spillover Effect" is obvious; FDI can improve the quality of China′s economic development, and it do not support the "pollution paradise" hypothesis in China; The interaction of FDI and environmental regulations significantly improved the quality of economic development, and environmental regulations have a certain "screening" effect on FDI; The results of the intermediary effect show that FDI will affect high-quality economic development through three pathways such as technology innovation, industrial structure and productivity effect; compared with the transmission channel of technological innovation and industrial structure on FDI, the effect of production efficiency mechanism is more obvious. FDI has significantly promoted the increase in productivity, and it is the main source and power that drives high-quality economic development; In general, FDI has a negative effect on high-quality economic development through technological innovation, which is contrary to theoretical expectation. Further analysis found that the impact of technological innovation and FDI on high-quality economic development has a significant threshold effect, which is reflected in different levels of technological innovation. Both technological innovation and FDI should reach a certain threshold level to promote high-quality economic development. Based on the above conclusions, this paper reveals the following policy implications. Firstly, we must increase the intensity of FDI, increase the level of opening-up, effectively bring into play the reversing effect of environmental regulations, and efficiently promote high-quality economic development. Secondly, we must adhere to the concept of innovation-driven high-quality development, and high-level opening to promote high-quality development. The local government should reasonably formulate the policies in different regions at different stages of economic development based on threshold conditions of technological innovation and FDI for economic quality to avoid the inefficiency of technological innovation and reduce the negative impact of FDI intermediary channels. In addition, due to the influence of the COVID-19 and changes in the domestic and international situation, China′s economic is facing great difficulties and challenges. The government should cautiously implement the economic stimulus policies and measures to prevent a large amount of capital from flowing to traditional pollution and overcapacity industries, guide capital to invest in advanced manufacturing, emerging and environmentally friendly industries, and promote the development of "new infrastructure", "new services", improve production efficiency, advocate a green economy, and achieve high-quality economic growth. 

Key words: FDI, technological innovation, high-quality economic development, environmental regulation, panel threshold model