To address the issue that intense air-water mixing, caused by the violent collision between water falling along the shaft wall of a drop shaft and the water body at the shaft bottom,may compromise the safe operation of the project, hydraulic phenomena were observed through physical model tests, the air-water mixing characteristics in the drop shaft were explored, the venting mechanism was analyzed, a systematic hydraulic optimization design of the shaft venting facilities was carried out, and a high-efficiency combined venting and bubble-reduction scheme, consisting of a semi-annular weir and three intermediate baffles, was proposed. The results show that the semi-annular weir can divert air-entrained flow away from the tunnel inlet.By extending the flow path and increasing the degree and frequency of streamline deflection, the intermediate baffles promote the collision, coalescence, and upward escape of micro-bubbles, thereby improving the efficiency of venting and bubble reduction, ensuring the safe and stable operation of the drop shaft across a wide range of water level fluctuations.