With the wide application of 3D games and the improvement of smart phone performance, the competition of the R & D and market of 3D mobile game products is becoming increasingly furious. Compared to ordinary computers, the hardware resource of mobile phone is greatly limited, so how to develop a 3D mobile game that can match the performance of PC platform 3D game has become a hot-topic in the field of mobile phone application. This essay analyzed 3D mobile game development framework based on Unity platform and Unity script execution flowchart, and with the rich development experience, this essay proposed optimization strategy and presented real examples ---- optimization experiment of 3D role-play mobile game, and further proves its feasibility and validity.