A composite peristaltic pump comprises a pump base, a mandrel, an assembling bearing, an upper pump head, a lower pump head, an upper pump casing, a lower pump casing, limit bases, pump head covers, clamping grooves, an electromagnetic base, pump casing covers and a stepping motor, wherein the mandrel is fixed on the pump base through the assembling bearing and fixedly connected with a shaft of the stepping motor, the upper pump head and the lower pump head are arranged on the mandrel in overlapped mode, the upper pump head is formed by a driving wheel, a driven wheel and a ratchet wheel mechanism, and the electromagnetic base is fixed in the pump base and controls moving, opening and closing of the upper pump casing and the lower pump casing through electromagnetic force. The clamping grooves are arranged at two ends of the pump base and are in shaft connection with the limit bases arranged at two ends of the pump base, and the flexibly rotating clamping grooves can be used for ensuring that positions of two pump pipes in the pump heads are reliable. The ratchet wheel mechanism is arranged between the driving wheel and the driven wheel, the driving wheel can drive the driven wheel to rotate unidirectionally, the upper pump head stops rotating when the motor shaft rotates in the reverse direction, and therefore the purpose of pumping liquid synchronously and evenly in the reverse direction in proportion is achieved.