The invention discloses a radiator and a hydraulic jet propulsion device and belongs to the hydraulic jet propulsion field. The radiator comprises a cooling oil tank which is provided on an outer side wall of an inlet end of an inlet pipe; the cooling oil tank comprises side plates, a cover plate, an oil inlet and an oil outlet. Through the installation of the cooling oil tank on the outer side wall of the inlet end of the inlet pipe and the installation of an oil inlet and an oil outlet on the cooling oil tank, the cooling oil tank is connected between a hydraulic cylinder and a hydraulic pump oil tank so that when a hydraulic control system works, high temperature hydraulic oil flows from the hydraulic cylinder to the cooling oil tank; plenty of water continuously passes through the inlet pipe so that when the high temperature hydraulic oil flows through the cooling oil tank, the heat is taken away by the water in the inlet pipe and therefore the high temperature hydraulic oil is cooled; the water in the inlet pipe is directly utilized for cooling so that there is no need to provide cooling water source which saves production cost; meanwhile, the water flow in the inlet pipe is large so that the heat dissipation effect is better.