The invention discloses a movable valve seat type spring loaded type relief valve. The movable valve seat type spring loaded type relief valve comprises a valve body provided with a cavity body. A water inlet and a water outlet communicated with the cavity body are formed in the valve body. A valve core and a valve seat are arranged inside the cavity body of the valve body. A spring is arranged inside a cavity of the interior of a front end cover. A spring ejection rod is installed at the top of the spring, and a spring base is arranged at the bottom of the spring. One end of the spring abuts against the spring ejection rod, and the other end of the spring abuts against the spring base. The valve seat comprises a two-stage step structure. The ascending end of the step structure is in clearance fit with the valve body and a sleeve. According to the movable valve seat type spring loaded type relief valve, a valve core king-rod structure is designed in the position of an injection inlet where fluid enters the valve core through the valve seat, so that the fluid power of the sprayed fluid is conducted to the valve core through a valve core king-rod, and the impact force and the corrosion to the valve seat by the fluid power are reduced; in addition, the step structure part of the valve seat makes contact with the two-stage conical surfaces of the valve core, so that a two-stage throttling valve port structure is formed between the valve seat and the valve core, and the effective partial pressure can be achieved.