The indoor simulation bench test of transmission is an important method of assessment,evaluation and promotion of its performance.Taking transmission as an example,a program load spectrum compiling method for transmission accelerated fatigue test is presented.The actual road load spectrum of automobile transmission is collected on Automobile Proving Ground in Dianjiang used wireless telemetry technology.The actual load spectrum is pretreated divided gear position,the second gear load spectrum is selected as an example.The frequency distribution matrix of load is obtained based on rainflow counting method,the distributions of mean and range are found to confirm with normal distribution and two- parameter Weibull distribution respectively.The mean of the normal distribution is 91.77 N·m,and the standard deviation is 163.27 N·m,the shape parameter of Weibull distribution is 1.346,and the scale parameter is 305.489,the distributions of load range and mean is independent.The two- dimensional load spectrum with 8×8 levels is established with joint probability distribution function.After two- dimensional load spectra is transformed into one- dimensional 8-level load spectra with variable mean method.Based on damage and low loading strengthening property of half shaft,the equivalent strengthening rule between strengthening loads is explored.By transferring the strengthening loads to the most effective level,the load loading frequency reduced,test efficiency is improved.