The invention discloses a nozzle of a low-speed diesel engine. The nozzle comprises a nozzle body formed by isostatically pressing cobalt-base alloy powder, wherein the nozzle body is provided with an inner nozzle cavity with a needle valve matching part; a shoulder part of the nozzle body at a port of the inner nozzle cavity is a rigid sealing plane used for matching with the needle valve matching part; the outer peripheral wall of the nozzle body is provided with four spray holes respectively being a first spray hole, a second spray hole, a third spray hole and a forth spray hole; the firstspray hole, the second spray hole, the third spray hole and the forth spray hole are sequentially and helically arrayed along the central axial line of the nozzle and communicated with the inner nozzle cavity; the outside of an edge port of the nozzle body is provided with a positioning groove used for determining positions of the spray holes. The nozzle of a low-speed diesel engine has novel structure, small volume, high temperature resistance, corrosion resistance and wear resistance and can meet the requirements on low oil consumption, less discharge, good reliability and long service life of an oil sprayer assembly.