Abstract: When motors with high or hyper rotating variation are used to drive sucker rod pumping systems,relatively high amplitude fluctuations of motor working rotating speed can take place.Taking account of such motor rotating speed fluctuations,the prediction model of behavior parameters of the sucker rod pumping systems is established.The model involves dynamic differential equations describing the motion regularity of crank,and wave equations describing the vibration of sucker rod string. Because of the nonlinearity of dynamic differential equations and the high degree coupling of dynamic and wave equations,it is rather difficult to make direct use of finite difference method to find out their numerical solutions.A kind of iteration method is applied to solving this problem in a quite smooth manner.The softwares developed on this basis can be applied with high accuracy.