The invention relates to the technical field of underwater vehicles and in particular relates to a pump-jet submerging unit capable of being worn on four limbs. The pump-jet submerging unit comprisesa control device, a pump-jet propulsion unit and an adjustable arm protector, wherein the control device is fixedly connected with an oxygen bottle by virtue of a first connecting piece; the pump-jetpropulsion unit comprises a closed chamber and a water pump; a motor, an electronic speed controller and a steering engine are arranged in the closed chamber; the water pump comprises a pump body, a plurality of water inlets formed in side walls of the pump body, and a water outlet formed in the bottom of the pump body; an impeller is arranged in the pump body and connected with an output end of the motor by virtue of a rotating shaft; and the adjustable arm protector is fixedly connected with the pump-jet propulsion unit by virtue of a second connecting piece. According to the pump-jet submerging unit disclosed by the invention, the pump-jet propulsion unit can be fixed on the four limbs of a diver, so that the flexibility of the diver in water is not influenced. Compared with the traditional propeller propulsion manner, the submerging unit disclosed by the invention is safe and can realize diving activity in shallow water.