Disclosed is a supporting oil sprayer oil return device of a diesel engine. A copper sleeve (7) covers the middle portion of an oil sprayer (6), a copper pad (8) is arranged on the lower portion of the oil sprayer in a sleeved mode, and the oil sprayer is vertically arranged in an oil sprayer mounting hole (D) of a cylinder cover (5). A high-pressure oil connecting pipe (4) is horizontally arranged inside a high-pressure oil connecting pipe mounting hole (G) of the cylinder cover (5), the front end of the high-pressure oil connecting pipe is connected with an oil inlet of the oil sprayer (6), and the rear end of the high-pressure oil connecting pipe stretches out of the cylinder cover (5) to be connected with a three-way connector (10). The oil sprayer mounting hole (D) and the high-pressure oil connecting pipe mounting hole (G) form an oil return cavity formed inside the cylinder cover (5). Fuel oil which is sprayed flows out from an oil return opening (H) of the oil sprayer (6), enters the oil return cavity, enters the three-way connector (10) through a three-way oil return opening (S), and then flows back to an oil tank through a fuel oil outlet (R) and an oil pipe (9). Structural design of the cylinder cover (5) is simplified, the functions of the high-pressure oil connecting pipe mounting hole (G) are expanded, interference with other parts by an oil return channel of the oil sprayer (6) is reduced, manufacturing and installing are easy, faults are reduced, and the performance of a main machine is guaranteed.