The utility model is mainly applied to the technical field of engines. The utility model relates to a cylinder cover oil sprayer hole machining device. The device comprises a hydraulic tool, a composite rough boring cutter, a composite semi-fine boring cutter and a composite fine boring cutter, the hydraulic tool comprises a vertical tool body. A tool positioning face is vertically arranged on theside face of the vertical tool body, a positioning cushion block and a positioning pin are arranged on the tool positioning face, a hydraulic rotating arm is arranged on the outer side of the tool positioning face, a positioning space is formed between the hydraulic rotating arm and the positioning cushion block, the hydraulic rotating arm is communicated with hydraulic oil ways, and the hydraulic oil ways are communicated with a hydraulic oil tank through oil pipes. Through reliable positioning of the hydraulic tool, machining of the whole oil atomizer hole can be completed through three times of tool changing. The traditional single-cutter hole-by-hole machining mode of the oil atomizer holes can be changed, the machining time can be effectively shortened, meanwhile, the labor intensityof workers can be reduced, and the surface roughness of the holes can be effectively guaranteed. Through cooperation of the three compound cutters, the stepped hole of the oil atomizer is machined inthe body.