Complex equipment such as wind turbine blades faces both performance degradation and random shocks. There are two interdependent relationships between these two failure modes: the interdependence between internal factors in the degradation process and the interdependence between degradation and shock processes. These characteristics pose challenges to reliability analysis. To solve this problem, a new mutually dependent competing failure processes (MDCFPs) model was proposed based on two MDCFPs models. This new model integrated two interdependencies. Taking the wind turbine blade stiffness degradation model based on Gamma process and the extreme shock model based on homogeneous Poisson process as examples, the accuracy and differences of three models were analyzed using the control variate method, and the influence of key parameters was studied. The results show that, under the same conditions, the new model's reliability is closest to the observed empirical reliability, with an absolute error of no more than 0.12. At the same time, the new model's reliability is lower than that of the two base models, with maximum absolute errors of 0.26 and 0.40, respectively. After adjusting the parameters of the new model, the absolute errors in reliability compared to the base models are limited to 0.03 and 0.02. These findings suggest that the new model effectively accounts for interdependencies among factors, prevents overestimation of reliability, and can replace base models, demonstrating broader applicability.