The utility model discloses a hand formula oiling device for speed reducer, it includes external gear pump, oil tank and oil pipe, external gear pump includes oil pump shell, be equipped with the last cavity and lower cavity of longitudinal symmetry in the oil pump shell, it feeds through the oil pump cavity body that forms transversal personally submitting " 8 " shape with lower cavity to go up the cavity, go up and internal the correspondence respectively of cavity and cavity of resorption be provided with gear and lower gear, it meshes with lower gear mutually to go up the gear, the both sides of the last oil pump cavity of lieing in of the oil pump shell body are equipped with the oil feed passageway respectively and produce oil the passageway, the position of the oil feed passageway and the passageway that produces oil is all corresponding with the position of engagement of lower gear with last gear, go up gear or lower gear teeth wheel shaft extension oil pump shell and be connected with drive arrangement, the oil tank passes through oil pipe and oil feed path connection, and the passageway department of producing oil is connected with the oiling hose. The utility model discloses simple structure, convenient, the easy maintenance of oiling basically do not receive the influence of speed reducer mounted position and height during the oiling.