Based on the evaluation opinions of domestic specialists about one loader hydraulic system of proper motion artillery, by using the knowledge of fuzzy mathematics, a model of fuzzy mathematics about reliability apportionment of the system was built. Statistic treatment and solution analysis of the weight set，value set and failure rate about the loader hydraulic system were accomplished. The problem that the judgment of the reliability about loader hydraulic system was not so accurate in the past was solved. It is valuable of certain referance to failure prediction and failure analysis of this type of loader hydraulic system.