Abstract: In order to study the factors affecting the lateral stability of the tricycle, according to the structural characteristics of the tricycle, the tricycle is simplified as a triangular prism rigid body, and the theoretical calculation models of roll critical speed and maximum roll stability angle are derived by using the balance principle of the moment of the non-copoint force system to the axis. Combined with the actual vehicle, the PC-Crash simulation test method is used to obtain the simulation test values of the critical roll speed and the maximum roll stability angle of the tricycle under different working conditions. Using MATLAB numerical analysis method, the theoretical calculation results are compared with the simulation test values to verify the feasibility of the theoretical calculation model. The research shows that, compared with the four-wheel vehicle, the lateral stability of the tricycle is not only related to the height of the vehicle center of gravity, but also related to the longitudinal distribution of the center of gravity. Measures can be taken to prevent tricycle rollover accidents from three aspects: people, vehicles and roads.