This paper made a profound discussion on the calculating method and fundamental elements in using inertia to make the pumping unit pumping and gushing, deduced the formula of the quantity of pumping with gushing theoretically, and, in turn, obtained the calculating formula of pumping efficiency of the well of pumping with gushing, thus providing us with a theoretical basis for elaborately designing the pumping parameters, creating the condition for well of pumping with gushing, and raising the efficiency of a pumping system,