The invention discloses a reliability evaluation method based on oil metal concentration of a special-vehicle transmission device, and belongs to the technical field of special-vehicle transmission devices. According to the reliability evaluation method, mathematical treatment is carried out on detection data of the oil metal element concentration in a fixed-time censoring bench test of the special-vehicle transmission device, a change rule of reliability along with testing time is obtained, a failure threshold of the metal element concentration is further combined, pseudo failure life corresponding to each test sample is obtained, and finally reliability evaluation is carried out on the special-vehicle transmission device through logarithmic normal distribution of the pseudo failure lives. The method accords with loss characteristics in a working process of the special-vehicle transmission device and overcomes the defect that according to an existing reliability evaluation method of the special-vehicle transmission device, only random failure can be considered, and loss failure cannot be described effectively; thus, an evaluation result is high in confidence level, and the information utilization rate is high.