提出了在进行机械零件设计过程中 ,使用基于 D- S证据理论实现模糊性与不确定性的推理 ,在实际构成设计专家系统时 ,引入信任函数、似然函数和类概率函数 ,使用证据理论建立不确定推理模型以及模糊集 ,可以实现一般机械设计系统决策。在本文中 ,将该理论应用于齿轮箱设计过程的设计参数、选型和几何参数的专家决策中 ,实现了一般轮类设计专家系统的构建 In the process of designing mechanical parts, the inference based on D-S evidence theory is used to realize the fuzziness and uncertainty. When designing the expert system, a trust function, a likelihood function and a class probability function are introduced. Using evidence theory The establishment of uncertain reasoning model and fuzzy set, can achieve the general mechanical design system decision-making. In this paper, the theory is applied to the design decision of gearbox design process, selection and geometric parameters of expert decision-making, to achieve a general wheel design expert system construction