This study analyzed the deformation law of rear axles with variable wall thickness under bidirectional horizontal extrusion and found that necking was accom-panied by upsetting deformation through theoretical calculation,numerical simulation,and experimental research.The sequence and occurrence of necking and upsetting deformations were obtained.A theory of deformation was proposed by controlling the distribution of temperature field.Effective processes to control the wall thickness of rear axle at different positions were also proposed.The ultimate limit deformation with a necking coefficient of 0.68 could be achieved using the temperature gradient coefficient.A new technology of two-step heating and two-step extrusion for a 13 t rear axle was developed,qualified test samples were obtained,and suggestions for further industrial application were put forward.