Abstract:In the design of mechanical part fitting, the factors that infl uence the selection of fi tting can be called evidences. After the introduction of evidences classifi cation and effect, a method of mechanical part fitting based on evidential reasoning is proposed. The vector quantization of main evidences combines the use of fuzzy expression and exact computation. Then, with other evidences, the result can be fi gured out. Examples show that this method can be applied to general mechanical part fitting design.