Failure rate and average failure rate play a very important role in the reliability research of mechanical products. They and average residual life determine the life distribution and reliability of structures. Based on the basic index of reliability measurement, the rela-tionship between fatigue reliability coefficient and reliability was deduced when the life distribution is two parameter Weibull distri-bution. A method for calculating the structural failure rate and average failure rate was proposed based on fatigue reliability coeffi-cient, and the corresponding calculation process was derived. Based on the existing fatigue life test data of integral lap panel structure, the proposed method and the traditional integral method are used to calculate the average failure rate and error analysis of integral lap panel structure. The results show that the formula is simple, easy to calculate, and has the characteristics of high accuracy and relia-bility. It is of great significance for FMECA and maintenance decision-making of mechanical structure.