It requires a damage tolerance assessment for all airframes and engines to set the inspection windows for safe operation. A certain rotorcraft main rotor yoke were analyzed with NASGRO model. The sensibility analysis of influence parameters in crack growth life has been done. In order to calculate the sensibility index of influence factors to crack growth life, the factors were divided into input parameters and crack growth model parameters. The results show that the input parameters have the following precedence ordering: fatigue crack growth threshold, fracture spectrum, initial crack, fracture toughness, the sensibility values are 11.25, 8.5417, 0.8333, 0.1125, respectively. The NASGRO model parameters have the following precedence ordering: n, p, C, q. the sensibility values are 6.0417, -3.9583, 1.25, 0.1812, respectively.