The invention provides a pressure adjusting assembly. The pressure adjusting assembly can solve the problem that an existing pressure adjusting assembly cannot effectively stabilize the pressure of engine oil in a main oil duct all the time. The pressure adjusting assembly comprises an adjusting threaded rod and a spring, wherein the adjusting threaded rod and the spring are installed in a pressure adjusting assembly section arranged at the tail end of the main oil duct, the adjusting threaded rod is connected with the inner wall of a slide way of the pressure adjusting assembly section in a threaded mode, and is tightly locked through a lock nut, a locating shaft of the adjusting threaded rod is sleeved with the spring, the bottom end of the spring is fixedly connected with the top surface of the adjusting threaded rod, the tail end of the pressure adjusting assembly section is sealed through an oil seal nut, and an oil drainage port is formed in the oil duct wall, close to the main oil duct, of the pressure adjusting assembly section. The pressure adjusting assembly is characterized in that an adjusting plunger is further installed in the pressure adjusting assembly section, a restraining groove is formed in the bottom end of the adjusting plunger, the top of the spring is embedded into the restraining groove, the top end of the spring is fixedly connected with the groove bottom surface of the restraining groove, the area of the top surface of the adjusting plunger is larger than the sectional area of the main oil duct, the height of the adjusting plunger is larger than that of the oil drainage port, and the adjusting plunger and the oil duct wall of the pressure adjusting assembly section are in clearance fit.