Actually, when an eccentric cam rotates around a fixed axis, it is the geometric center of eccentric cam that moves in simple harmonic motion (sine/cosine motion), under certain conditions, the components (such as piston) driven by the eccentric cam do not move in the same simple harmonic motion, therefore some problems, such as the change in pressure, can be caused when double eccentric cams are applied in some process equipment. Therefore, on the basis of analysis of the motions of the double eccentric cams used in process intensification equipment, the causes that the motions of the two pistons driven by the eccentric cams are not completely symmetrical and this may cause the pressure in the equipment to change is found out, and the relevant solutions are proposed.