Hybrid powertrains with planetary gearset (PG) have been widely used. However, there are few types of powertrains in use, and more powertrains have not been found. Based on the principle of organic chemistry, a design and screening method of multi-mode 2-PGs hybrid powertrain is proposed, which is divided into five stages. First, powertrains are expressed in the form of molecules. Second, powertrains split into the libraries of PGs and power sources. The power sources can be mutually identified to construct new library. Third, the mode switching rules are defined to screen power source group. Fourth, two libraries interact with each other to promote the generation of new molecules, namely, new powertrains. And the more modes, the greater the potential for performance. Powertrains are screened with mode richness theory firstly. Finally, taking the comprehensive evaluation of power performance and fuel economy as the optimal standard, powertrains are screened and evaluated twice. Through the method, hybrid powertrains with smooth mode switching, simpler structure, and optimal power and economy can be obtained.