An autonomous lubricating device of a launching vehicle reducer comprises an input shaft, an input end bearing, a small teeth difference pin shaft support bearing, a small teeth difference mechanism, a lubricating pump and an output shaft. The lubricating pump comprises a shell body, a plunger, an external thread oil inlet steel ball, an internal thread oil inlet steel ball and screws, wherein the tail of the input shaft is provided with an internal spiral groove and an external spiral groove. The autonomous lubricating device of the launching vehicle reducer is sleeved with the shell body and embedded with the plunger inside so that the switching of the positive and negative rotation and the lubrication of the internal groove and the external groove are realized through the opening and closing of the steel ball. Lubricating oil is sucked through an oil inlet of the shell body, transported to the central pores of the input shaft through the spiral grooves and flows out from the oil outlet of the input shaft to lubricate the bearing. The revolving speed of the input shaft is different from that of the output shaft so that the lubricating pump is enabled to lubricate. The autonomous lubricating device of the launching vehicle reducer is simpler in structure, does not increase the volume of the reducer and reduce the precision and the transmission efficiency of the reducer, is not limited by the structural arrangement, and can provide sufficient lubrication under the condition of the positive and negative rotation of the input shaft.