Based on fracture mechanics

finite element software ANSYS was adopted to calculate the stress intensity factor（SIF）which is used to characterize the surface crack propagation speed of stay-cables steel wire;The law that shows how the crack shape parameters influence steel stress intensity factor correction coefficient F was analyzed and two-parametric expression of the F was fitted out;Then

a simple method of forecasting the depth of crack was proposed through the comparative analysis of the deepest point and the edge point of crack;Finally

the difference was compared between nominal stress approach and fracture toughness standards which is an analysis method of residual strength of steel wire with crack based on the fracture mechanics;The results from this research is of value to further improving the existing performance assessment methods for stay cables with cracks.