The invention relates to a driving axle main reducer. An existing driving axle main reducer has the problems that the oil stirring loss is large, the driving efficiency is reduced, and the temperatureof a driving axle is too high, so that the driving axle main reducer is provided to solve the problems. The driving axle main reducer comprises a bracket assembly, a differential mechanism assembly,a driven spiral bevel gear, a driving spiral bevel gear and a first oil baffle plate, the bracket assembly comprises a bracket, a left bearing seat and a right bearing seat, and wherein the left bearing seat and the right bearing seat are arranged on the bracket; and the right end of the first oil baffle plate is fixed to the right bearing seat, the front end of the first oil baffle plate is located below the driving spiral bevel gear, the rear end of the first oil baffle plate is located at the position above a drive axle gear oil level line, and the left end of the first oil baffle plate islocated on the radial outer side of the driven spiral bevel gear. According to the driving axle main reducer, the driven spiral bevel gear and the differential mechanism assembly serve as driving parts with relatively fast rotating speed, the first oil baffle plate covers the part, located below gear oil, of the two driving parts, so that the effect of stirring the driving axle gear oil can be effectively reduced, and therefore the technical problem that the oil stirring power loss of the driving axle main reducer is large is solved.