1n this paper , the vertical fatigue crack propagatlOn rate of CCT sample under constant amplitude load spectrum was tested. Least-squares fit the Paris equation's constant c and n , and the statistical analysis of c and n 1S presented. The reasonableness of c , OlS tested. Based on the expenmental data ,the material's P-a-N curves and sample's a-N curves are gamed. The results of the analysis lay a foundation for the damage tolerance analysis of Aircraft Frame.