The use of structural durability analysis technology can effectively improve the economic efficiency of aircraft structures while ensuring their reliability. This paper utilizes the structural durability analysis technique to study the initial fatigue quality （IFQ） of a typical fatigue structure of 7B04-T651 high-strength aluminum alloy under the action of flight load spectrum of a certain type of aircraft. Firstly， the maximum likelihood estimation method is applied to the parameter estimation problem of crack initiation time distribution based on three-parameter Weibull distribution. The Monte Carlo method is used to verify the correctness of this approach. Secondly， fatigue tests under three different stress levels are carried out on the flight load spectrum. The logarithmic sample moment approach is proposed to process the equivalent initial flaw size distribution to obtain its general model. In addition， the initial fatigue quality model describing the typical structure is established， which verifies that the equivalent initial flaw size （EIFS） is less than the allowable 0.125 mm. By analyzing the initial fatigue quality of the typical structure， the correctness and practicability of the generalization method is demonstrated， and the life estimation model of this typical structure is built under different stress zones， different specified crack sizes and different reliability levels.