The sticking phenomenon of a kind of oil pump,encountered in its pre-production,was analyzed.By using the finite element analysis software Ansys combined with practical experiences,a more comprehensive and reasonable analysis method was proposed.The oil pump was analyzed under extreme experimental conditions.It is found that the main factor causing the oil pump's sticking is the unreasonable dimension tolerances of the driven shaft and one of the driven gears.According to that appropriate measures were adopted for design improvement.The improvement scheme was validated through experiments,and the rationality of the analysis was finally proved.