In order to realize rapid evaluation on high reliability and longlife products，this paper uses constantstress accelerated life test method，sets up statistical model of inverse powerWeibull in which，suppose that the failure mechanism of Weibull distribution products is the same under each level of experiment stress，and that the relation between scale parameter and stress level demonstrates loglinear link，the unknown parameters of the statistical model of inverse powerWeibull，shape parameter and scale parameter of Weibull distribution are estimated by least square estimation. The statistical analysis of constantstress accelerated lifetest data of a transformer shows that the statistical model of inverse powerWeibull is feasible，loglinear acceleration model is obtained，the least square estimation of reliability indexes of a kind of transformer at normal voltage stress 25.8 KV is received.