Abstract: Focusing on the increasingly fierce Sino-US technology competition and the Tech Decoupling proposition of the US, this paper constructs a new technology proximity index, uses patent application data to measure the degree of competition between the US technology layout in China and China's independent technology layout, and analyzes the trend of Tech Decoupling in various fields. The results show that the overall degree of competition between the two countries has been stable at a high level since 2010, but after the US unilaterally launched the cold war on science and technology against China, the technology proximity index continues to decline, and the trend of Tech Decoupling is obvious. The analysis of technology proximity at the field level shows that after 2018, the US applicant adjusts patent layout strategies in six areas, such as highly competitive computer technology and digital communication, reducing the correlation between US and China's technology layouts, most likely driving Tech Decoupling in these fields. In the last part, some suggestions on how to response Sino-US Tech Decoupling are put forward.