Abstract: It is important to estimate two coefficients a and b of accelerated equation in accelerated life test, and such a and b are often estimated by means of weight least square estimator （WLSE）. Its algorithm is simple, but it cannot get a minimum variance because of ignoring the correlation between estimations of a and b. In this paper we designed a new quasi-BLUE for a and b. It can not only make the variance approach minimum, but also make the algorithm simple as well. Finally, this paper gave lower bounds of relative efficiency of WLSE and quasi-BLUE.