In order to obtain more working manners of cam motors,a double- rotor cam motor,whose displacementvaries with the inlet connection mode,was designed.Then,the rational torque and the speed of the motor at fixedflow and load were calculated under different connection conditions,and the torque ripples in different workingmanners were compared. The results show that the four input ports of the double- rotor cam motor are of six differentoutput combinations,three of which,namely the combinations respectively of two inside motors,two outside motorsand two inside/two outside motors,are of small output torque ripple; and that there are two kinds of differentialconnections of the double- rotor cam motor,in which the two outside/two inside connection can achieve low torque,high rotational speed and a theoretical torque ripple of zero.