Abstract:A series of basic formulas,which are used for designing saw chains and sprockets,were built upon contour parameters of new-type sw chains and sprockets by reference to geometry of usual chain drives. The formulas concern two kind of saw chains with same pitch and different pitch and three kind of sprockets,which are rim sprocket,spur sprocket and nose sprocket. Bumping, point contact,sliding,climbing, side clearance and fluctuating tension occur if the pitch of chain differs from the pitch of sprocket so that wear-and-tear of chain and sprocket,loss of power and probability of chain breaking and coming off increase and steadiness of cutting procedure decreases.