The utility model discloses a rock core sampling drilling machine. The device comprises a base, a drill bit, a clamping part, a water sealing assembly and a driving device, wherein the clamping part is arranged on the base; the drill bit is positioned above the clamping part; the distance between the drill bit and the clamping part is adjustable; the driving device drives the drill bit to rotate by driving the drill rod, the drill bit comprises at least three blades, a gap is formed between every two adjacent blades, the distance between every two adjacent blades ranges from 1.5 mm to 2.5 mm,the drill bit is connected to the bottom of the drill rod, and the outer diameter of the drill bit is larger than that of the drill rod. By adopting the device, the sediment flowback capacity is increased, the flowback rate is increased, the drill bit is prevented from being blocked, the drill bit is effectively lubricated and abraded in the sampling process, the service life of the drill bit is prolonged, the cost is saved, the sampling efficiency is improved, and a sample is prevented from being broken, so that the integrity of original geological data is better kept, the sampling efficiencyis improved, and time and cost are saved.