In polar coordinates,analytical method on field of line is applied to deduce the solution ModeⅡ cracking of elastic-perfectly-plastic material in form of power series in elastic-plastic zone and elastic-plastic boundary(scope of plastic zone)near to stress cracking line of elastic-perfectly-plastic material ModeⅡ plane under uniform shear action,on the basis of equilibrium equation and Mises yield condition.The stress matching of each direction on the plastic-elastic boundary gives up the assumption of elas...