Due to the complex functional structure and harsh working environment of wind turbines, their degradation states are characterized by diversity, and the failure forms are often the result of the coupling of multiple faults, so it is not comprehensive to adopt the performance degradation process of one variable alone as a model for assessing the life and reliability of wind turbines. In order to more accurately reflect the correlation between internal and external performance indicators of the system, a failure physics-based multi-fault reliability modeling method for wind turbines was proposed. Firstly, the operating environment and fault characteristics of wind turbine under multi-stress coupling were analyzed, and the life distribution function was obtained by the failure physics-based reliability simulation analysis method and used as the marginal distribution function. Secondly, the two-stage estimation method was introduced to estimate the parameters of the model of Copula function when considering the failure mode correlation. The optimal Copula function was determined by comparing the rank correlation coefficient and squared euclidean distance of different types of Copula functions. Finally, a simplified wind turbine reliability model under multi-failure mode coupling is established by using Skla's theorem and the idea of stepwise analysis. The results show that the reliability results obtained when considering the correlation of reliability indexes are more reasonable, while the method avoids the conservative estimation of wind turbine life prediction and reliability assessment, and has better practicality and operability.