Structure-simplified pressure control system based on fixed displacement oil pump

The invention provides a structure-simplified pressure control system based on a fixed displacement oil pump. The fixed displacement oil pump, a pressure limiting valve, a switch electromagnetic valveand a main oil way are included. The fixed displacement oil pump comprises an oil inlet cavity and an oil outlet cavity. The pressure limiting valve comprises a first pressure feedback cavity, a plunger, a transfer chamber, an oil inlet cavity connector, an oil outlet cavity connector, an oil discharging port, a second pressure feedback cavity, a valve sleeve and a return spring. The oil outlet cavity connector constantly communicates with the oil discharging port through the transfer chamber. The main oil way is connected to the first pressure feedback cavity and the second pressure feedbackcavity of the pressure limiting valve through two independent oil paths, the switch electromagnetic valve is arranged on an oil path between the first pressure feedback cavity and the main oil way, and the second pressure fee