The proposed hydro-mechanical slot perforator for well drilling is a device designed for opening productive formations in at least two projections forming high quality slots. The perforator includes a casing, housing a piston-pusher, and a cutting assembly, located below the piston-pusher, including extendable cutting tools and a mechanism for extending thereof, formed as a double-arm (lower and upper) lever (or a balance beam), whose arms hold the cutting tools. A deflecting wedge is mounted on a mobile shaft under the lever. The shaft rotates when the lower arm interacts with the wedge, while the piston-pusher moves down. The piston-pusher is designed as a wedge-piston acting on the upper arm, extending the top cutting tools out, resulting in the wedge-piston and the deflecting wedge creating oppositely directed forces acting simultaneously upon the upper and lower arms. Another embodiment is proposed where an augmented cutting assembly includes more than two cutting tools.