Abstract: A diaphragm pump includes a driving assembly, a pump body, a connecting rod assembly, a photoelectric shielding sheet, and a photoelectric sensor. The driving assembly includes a base seat and an electric motor provided to the base seat. The pump body is connected to the base seat to define a chamber. The connecting rod assembly is disposed in the chamber and includes an eccentric wheel connected with an electric motor shaft of the electric motor. The photoelectric shielding sheet is separately provided to the eccentric wheel and rotates synchronously with the eccentric wheel and the electric motor shaft. The photoelectric sensor is provided to the base seat and cooperates with the photoelectric shielding sheet to detect a rotational speed of the electric motor shaft and send a signal to a motor controller. The motor controller adjusts the rotational speed of the electric motor shaft according to the signal.