The invention provides a machining grinding device, and is suitable for the technical field of machining of steel rust removal grinding machines. The machining grinding device comprises a base, a grinding roller, a driving motor, a second gear shaft and a third gear shaft, wherein the grinding roller is rotationally connected to the base, one end of the grinding roller is coaxially and fixedly connected with a first gear shaft, the driving motor is coaxially and fixedly connected with the other end of the first gear shaft, the second gear shaft is slidably and rotatably connected to the base,the third gear shaft is connected to the base in a sliding and rotatable mode and is meshed with the first gear shaft and the second gear shaft, the shaft end of the third gear shaft is connected withthe shaft end of the second gear shaft through a connecting piece, by changing the position of the third gear shaft on the base, and adjusting the distance between the second gear shaft and the grinding roller, and grinding of steel pipes of different diameter specifications is achieved. According to the grinding device, the distance can be flexibly adjusted according to different diameter specifications of the steel pipes, the adjusting method is simple and convenient, applicability is high, the device principle is simple, and manufacturing cost is low.