The invention discloses a control method of assembly press-mounting stroke and a force value of a water pump of an automobile engine and a device thereof. The method comprises the following steps: a pressure sensor is arranged on a press; the press mounting head of the press is provided with transmission elastic slices which have adjustable relative position and are insulated with the press mounting head; the main pressure valve of the press is connected with a pressure maintaining valve in parallel; a solenoid valve is arranged in the front of the pressure maintaining valve; the pressure regulated by the pressure maintaining valve is lower than that regulated by the main pressure valve; the press, the pressure sensor, the transmission elastic slices and the solenoid valve are all connected with a PLC controller; and the whole press-mounting process is controlled by the PLC controller, thus ensuring that unqualified workpieces can be discovered in time in the process of press mounting, ensuring high assembly precision, and avoiding the workpieces from being damaged by an overlarge force.