The invention discloses a drilling device used for metal machining. The drilling device comprises a working platform and a support structure. The upper end of the working platform is equipped with a handle locking structure. The support structure is arranged at the lower end of the working platform and comprises a first support rod and a second support rod. The lower end of the support structure is equipped with rollers. The outsides of the rollers are equipped with roller brakes. The upper end on the left side of the working platform is provided with an air cylinder. The upper end of the aircylinder is equipped with a piston. The piston is connected with a second connecting rod through a first connecting rod. The upper end of the second connecting rod is equipped with scale lines. The outside of the second connecting rod is equipped with a baffle board. The lower end of the second connecting rod is provided with drill bits. The inside of the working platform is equipped with a cavity. The drilling device used for metal machining has the following beneficial effects: the scale lines replace manual lineation and drilling; by arranging the multiple groups of drill bits, multiple groups of holes can be drilled; and the baffle board can block chippings. The drilling device used for metal machining is novel in structure and high in working efficiency.