Tolerance distribution method

The invention discloses a tolerance distribution method, which comprises the following steps of: firstly, constructing a dimension chain equation, and meanwhile, obtaining a machining capability index of part machining; a random sample set of all parts is generated through the machining capacity indexes and the dimension chain equation, finally, a corresponding virtual assembly parameter set is obtained through virtual assembly of the random sample set, and then a corresponding success rate is obtained through comparison of the virtual assembly parameter set and an assembly qualification criterion. Determining whether the assembly tolerance distribution of each part is qualified or not; according to the method, the obtained random sample set is combined with the actual processing capacity of a factory by introducing the processing capacity index, so that the accuracy of the random sample set is improved, the accuracy of simulation assembly and tolerance design is improved, the error rate of tolerance allocati