A generalized Weibull competing failure mode approach for accelerated life test was demonstrated good approximation in reliability prediction. This paper expands this approach to confidence interval estimation and sensitivity analysis. The results show that the parameters a(subscript i) and b(subscript i) are all positive correlated to the reliability, and their sensitivity curves present similar half-sine curve. As well as the sensitivities of reliability vs. parameters β(subscript a, i) and β(subscript b, i) have something to do with the characteristic life and environmental loading, but the tendencies of their responding sensitivity curves are varied on the contrary.