To has built mathematical modeling of system, in order to solve fibrillation not regularly appeared even crawl phenomenon in the feed phase of the hydraulic cylinder in HCZW5072 machine tool, on this basis, we analyzed the failure mechanism, thus established the ways to solve the fault, and better solved the fault. According to the actual situation, therefore, to can establish a mathematical model of system, we can analyze the further cause of the failure, and more likely obtain the method to solve the problem. It is an effective way to solve the problem of the mechanical engineering.