The invention discloses a reliability evaluation method for a gear pair of a high-pressure internal gear pump. The method comprises the following steps: firstly, defining multiple failure forms of a high-pressure internal gear pump gear pair, and establishing a reliability performance function of each failure form; secondly, calculating the failure probability of each failure form by adopting a saddle point approximation method based on a high-order moment; secondly, constructing an importance measurement model of each failure form of the gear pair of the high-pressure internal gear pump; andfinally, establishing a multi-objective multi-constraint reliability optimization model of multiple performance indexes of the gear pair of the high-pressure internal gear pump. According to the method, the influence of various failure modes of the gear pair of the high-pressure internal gear pump on the reliability of the system is considered, and a plurality of performance indexes required to besimultaneously met by the high-pressure internal gear pump are also considered, so that the working performance of the high-pressure internal gear pump is improved while the gear pair obtained by themethod meets the reliability requirement.