An analysis model for the cracked plate of blade was established using fracture mechanics method.Firstly

the weight function for blade containing a single edge crack was derived from one reference stress intensity factor under uniform load.Secondly

the stress intensity factor at the tip of crack of rotating blade was calculated using weight function method.Finally

critical rotate speed of blade was inferred on the basis of fracture criterion.The analysis of examples shows that the depth and position of crack in blade have much influence on the stress intensity factor and critical rotating speed.