The time between failures, two groups of failure data of foreign highend gantry machining center, were collected by failure truncated testing. MTTFF and MTBF in different truncated number were calculated by the traditional method of reliability analysis. Then, the weights of MTTFF and MTBF of different samples were determined by dynamic weighting method. Eventually, the evaluated systems were sorted by Borda count function. The results show that A2 group is significantly better than A1 group. And the dynamic weighting method in multiple failure truncated testing could fully reflect the difference of the evaluated object both in the quality and quantity, which is a feasible method for reliability evaluation of gantry machining center.