The invention discloses a brake pedal force simulating device, which is characterized in that a cylinder with a control element is arranged on a rack; a piston rod of the cylinder is connected with a connector through screw thread; a synchronous plate extended to one side is fixedly connected to the connector; a pressure sensor is arranged at the front end of the connector, and the pressure sensor is propped against a brake pedal arranged on the rack in a direction of treading the brake pedal by using a roller at the front end of the pressure sensor; and a popup displacement sensor parallel to the piston rod is arranged on one side of the cylinder, and a contact of the popup displacement sensor is propped against the synchronous plate. The brake pedal force simulating device serving as anautomobile braking system test device can realize simulation of a process of treading the brake pedal, and has the advantages of simple structure, convenient arrangement, accurate control and high automation degree.