The invention relates to a rear-end gear chamber structure of a diesel engine. The rear-end gear chamber structure comprises a timing gear chamber cover, a rear-end plate body and a flywheel shell, wherein the middle of a left plate body in the rear-end plate body is connected with an air compressor gear, an oil pump gear and a third idle gear, the middle of an upper plate body is connected with afirst idle gear and a second idle gear, a camshaft gear is arranged on the upper plate body, a crankshaft gear and an oil pump gear are sequentially arranged in the bottom vacancy opening from top tobottom, and the front and back surfaces of the rear-end plate body are connected with a cylinder body/ a cylinder cover, the timing gear chamber cover/the flywheel shell respectively; the bottom surface of the cylinder body is connected with an oil pan, the top surface of the cylinder body is connected with the bottom surface of a housing of the cylinder cover through the cylinder cover, the right end of the housing of cylinder cover is connected with the top of the timing gear chamber cover, the bottom of the timing gear chamber cover is in wedge connection with a gear chamber cover matchinggroove formed in the top of the flywheel shell through a cover downward extending end. The rear-end gear chamber structure has the advantages of being convenient in manufacturing, assembling, maintenance and adjustment of gear system, light in weight, high in overall rigidity, and good in noise reduction effect.