Although the Weibull distribution is widely used in a variety of reliability applications, difficulties in its treatment, particularly in three parameter cases in the maximum likelihood estimation, hinder us from using the distribution. The extended Weibull distribution proposed by Marshall and Olkin (1997) can avoid the difficulties which appear in the conventional Weibull distribution models. This paper shows the maximum likelihood estimation method in the extended Weibull distribution model. The paper also illustrates some typical applications for breakdown voltage estimation in which the extended models are superior to the conventional Weibull models. The central discussion is whether the shape parameters in the extended model accomplish the mass shifting effect of the distribution.