The invention discloses an automobile half-shaft phosphorization process. According to the technical scheme adopted by the automobile half-shaft phosphorization process, the automobile half-shaft phosphorization process is characterized in that the phosphorization treatment is carried out on an automobile half-shaft in order to completely clear away and find oxide scales, oil stains, concealed cracks and residual impurities in the quenched automobile half-shaft, and the surface of the half-shaft is black, and the automobile half-shaft phosphorization process comprises the following phosphorization technological processes: carrying out degreasing pretreatment, degreasing, cleaning with hot water, washing with cold water, carrying out ultrasonic wave rust removal, cleaning with warm water, carrying out activating treatment, phosphating, washing with water, carrying out ultrasonic wave rinsing, cleaning with a chemical agent and drying.