For the slag-blowing effect of a conical laser processor in the cooling hole machining process of aeroengine hot parts， the flow field characteristics near the jet impinging on the aperture plate and its influencing factors are investigated. For the jet structure of coaxial high-pressure gas impinging on a flat plate with blind holes， numerical simulation methods are used to analyze the comprehensive effects of different inlet pressures p_int （0.2—1.5 MPa）， jet spacing H/D_e （3.6， 5.6， 7.6） and impact angle α （30°， 45°， 60°， 90°） on the gas dynamics performance near the blind holes. The results show that when H/D_e is 3.6， with the increase of inlet pressure， the gas dynamics performance near the blind orifice shows a tendency of gradual improvement followed by a drastic decrease， and the better working pressure is 1 MPa； when the jet spacing H/D_e reaches 5.6 and above， the aerodynamic level of the gas flow near the blind orifice can be improved by appropriately increasing the nozzle pressure， but the enhancement is limited. As the impact angle α decreases， the outflow mass flow rate in the blind hole gradually increases， and when α is 30°， it is about 11 times higher than that of the vertical jet， but the shear flow of the gas on the impact surface becomes weaker as the impact angle decreases.