There is inevitably large loss of fault information in vehicle reliability information collection, which results in inadequacy of the fault date. For this reason, the fault information loss compensation method of vehicle was studied in this paper, and the law of information loss was analyzed. Based on the existing study of reliability, considering the average loss rate, this paper built a distributing function to accumulate the loss fault information, especially discussed the dispose of loss rate, and finally elaborated the fault information loss compensation method of vehicle by an actual reliability design. The result showed that the method can overcome the evaluation result on the high error due to the loss information, and it accords with the actuality of the reliability of vehicle.