Green transformation is an important part of promoting high-quality development. The key to achieving green transformation lies in green technology innovation. However, the academia has not yet carried out analysis from the perspective of spatial agglomeration of digital economy industries. Based on the panel data of 30 provinces and cities （Due to the lack of data，the statistical data mentioned here do not include the Hong Kong Special Administrative Region，Macao Special Administrative Region and Taiwan Province.） in China from 2013 to 2020, this paper analyzes the impact of spatial agglomeration of digital economy industries on green technology innovation and its regulatory mechanism. The study found that the impact of spatial agglomeration of digital economy industry, digital economy manufacturing industry and digital economy service industry on green technology innovation was "inverted U-shaped", all passed the 1% significance test, the impact degree decreased in turn and there was a lag, indicating that the impact of digital economy industry collaborative agglomeration on green technology innovation was stronger. By calculating the inflection point value, it is found that most of the central and western provinces and cities are on the left side of the "inverted U", and some eastern provinces and cities have exceeded the inflection point value. After introducing the regulatory variable of environmental regulation, it is found that it can strengthen the "inverted U-shaped" impact of spatial agglomeration of digital economy industry and digital economy manufacturing industry on green technology innovation, and the lag is obvious. This study provides policy inspiration for provinces and cities in China to accelerate the green transformation of economic development mode, and also provides practical reference for improving regional green technology innovation capability.