Yu, Yi and Ma, Lin and Gu, YuanTong and Zhou, Yifan (2008) studied the three bootstrap methods, which have been applied to build confidence intervals for the lifetime distribution calculated by Gamma degradation models. The bootstrap calibration is conducted to assess the coverage probability of the estimated confidence intervals. The calibration shows different Gamma processes, these three bootstrap confidence interval generation methods will have different coverage accuracy. For the basic Gamma process, the bootstrap percentile produces the best results while the bootstrap-t methods are conservative and bias corrected & accelerated (BCa) is slightly anti-conservative. For the Gamma process, considering random effects, the three methods result in quite different outcomes. The BCa intervals are anti-conservative and have coverage probability closer to the nominal value while the other two confidence intervals vary around the nominal value. The BCa method produce reasonable results for both basic and random effect Gamma models.