Mining ball mill girth gear is the key transmission component of mine mill, which is mainly driven by electric motor to drive the rotation of pinion, and then the pinion drives the rotation of girth gear mounted on the cylinder, so that the ball mill can rotate. The machining accuracy of the girth gear is especially important when the girth gear is connected with the end cover and the cylinder. The accuracy of the girth gear directly determines the working performance, bearing capacity and service life of the ball mill. Our company generally adopts the processing method of three times turn-milling and two times milling teeth for the girth gear of mining mill. After long-term practice, this method is very reasonable and which is a processing technology with great reference value.