A valveless piezoelectric pump with single bimorph and double chambers was put forward for improving its flow rate. Some elastic curved surface differential equations of circular piezoelectric composite laminates were derived from the theory on the elastic thin plate bending with small deflection. The structure and working principle of the piezoelectric pumps consisted of one PZT bimorph to fabricate two chambers were introduced. The relations of structure and flow rate were analyzed by comparing with the single bimorph and single chamber piezoelectric pump. The valveless piezoelectric pump with single bimorph and double chambers was designed and fabricated. It has unique structure and high flux output. Experimental results show that the flow rate of piezoelectric pump with single bimorph and double chambers is obviously improved comparing with the flux output of the single bimorph and single chamber piezoelectric pump.