Interface is studied to solve the heat dissipation problem of the LED street lamp, improve the stability of the overall performance of lamps and promote the LED luminous efficiency. Firstly we analyzed the rationality and defects for interface of LED street lamp, such as modules fixed by four positioning Screws and Zhaga consortium of the modules. Thus we summed up three characteristics which high power LED lighting module interface should possess. According to the actual work environment and installation conditions of LED street light in our country, this article illustrates another kind of Wedge interface application in the modular LED street lamps, which is of efficient heat dissipation, convenient installation, and easy upgrading. By means of theoretical analysis and numerous practical tests, the technical advantages and generalizability of wedge connection of the LED modules are verified.