According to the quantitative description criterion of the fuzzy logic inference, the mathematical model and the precedures for reliability distribution are expounded, and the reliability of the beam pumping unit system is distributed by using the above-mentioned methed. 根据模糊逻辑推理的定量描述原理,论述了该方法的数学模型及分配串联机械系统可靠度的步骤,给出了应用该方法对游梁式抽油机系统进行可靠度分配的实例。