The accurate assessment of aircraft structure damage risk is the premise of establishing reasonable, economic and reliable maintenance intervals. While many studies have proposed damage risk assessment methods for aircraft structures, these methods lack the quantification of risk. This paper proposed a risk assessment method of aircraft structure damage maintenance interval considering fatigue crack growth rate and crack detection rate. The damage process of aircraft structure was simulated by Monte Carlo simulation to realize the quantitative assessment of aircraft structure damage risk and maintenance interval. Taking an aircraft fleet as an example, the damage risk of its wing structure was simulated and analyzed. The results show that if the risk is controlled within a reasonable range, the maintenance interval should be shortened to 16 flight hours. At the same time, through the analysis of the risk classification standard and the crack detection rate, the quantitative evaluation of the risk classification standard was realized.