Provided Planetary Mill Gearbox is manufactured from high alloy steel and heat treated for case carburizing to achieve optimum strength and wear resistance. This gear box is ground to reduce noise level and optimized maximum root strength and minimum sliding contact to ensure high efficiency. This gearbox can be installed with any size of mill. Provided gearbox is noiseless and hassle free and mills runs smoothly. Further, offered Planetary Mill Gearbox is compact and flexible structural shape, noise-optimized construction, high-performance gear units as a result the transmission of high torques, low maintenance designs and high availability.