On the basis of studying both at home and abroad, not only the orientation of the corn harvester rear axle pivot had been considered, but also the track width differences between front axle and rear axle had been taken into account, thus a more accurate quasistatic lateral stability mathematical model was constructed. Then lateral stability experiment and simulation analysis were carried out in order to verify the validity of the model. Accordingly the lateral stability influence factors were obtained. Afterwards, each influence factor was firstly set at a certain range of values, then the value range of each influence factor was converted into an identical range \[-1,1\], taking advantage of encoding transform. Therefore the curve of lateral stability indicator λ changing with the varying of different influence factors could be drawn in the same picture which could directly show the impact extent each factor on the lateral stability. The analysis results showed that the main influence factors of corn harvester quasistatic lateral stability were wheel base x, the height of corn harvester center of gravity h, the distance between the center of gravity and front axle a, as well as front axle track width t1. In the end, this paper also put forward several measures to improve the lateral stability of the whole machine. When the center of gravity is lowered by 100mm, the load ratio of the front and rear axle is increased to 4, as well as the symmetric machine model is adopted. The result shows that the alteral critical angle of the corn harvester can be increased from 24.8° to 29.52° and the lateral stability can be raised by 19.03%. The establishment of corn harvester quasistatic lateral stability mathematical model can provide a foundation for corn harvester overall arrangement and structure design.