The author discussed the calculation of traction force for lift system consist of complex pulley and steel reeving. By two quite other derivation methods it is proved that the formula delivered in M.3, Annex M, EN81-1:1998 is full of prunes, not only the masses of suspension rope and the moments of inertia of suspension pulley, but also the moments of inertia of pulley for tension device, the convert dynamic force are out in their reckoning completely. Further more, the author pointed out some nonstandard formats for mathematical expression, and ultimately gave out a universal formula, it can be applied for any reeving rate.