Abstract: This device relates to the fields of mining, specifically oil and gas industry, hydro-geological, geological engineering and water supply industries and is intended for cutting slot-shaped seats in well side zones of producing formation by hydro-abrasive blast. The determined task is solved by introducing essential changes into the known device for construction of cutting slot-shaped seats from the well wall inside the rock consisting of the hydro-abrasive jet generator connected with the perforator through the pump-and-compressor tubing string; the perforator is put into the casing pipe and has two diametrical nozzles which are directed at the well wall; there is a ball valve at the perforator end, as well as devices for adjustable partial unloading of PCS, PCS weight measuring device, abrasive jet pressure measuring device and the sealer for sealing of wellhead.