Abstract: In order to improve the prediction accuracy of service life of aeroco-mpressor blading, especially concerning its vibrating loading, it is necessary to carry out the following researclhes. Firstly, the load acting on the bloades is recorded inflight according to randomly sequencing mission profiles of various types of engines. Secondly, this field load is to be simulated in laboratory.In this paper, a technique for the simulation of the blade randomly vibrating spectrum has been investigated. A mathematical model for a step-load spectrum under which the blade fatigue damage is equivalent to that of in-service flight load has been derived. Using APPLE I interface system and 6502 machine language programme to deal with the vibrating spectrum, the step-load spectrum which is extraordionarily suited to microcomputer programming load control for fatigue test is obtained.