The invention relates to the field of ocean detection, in particular to an underwater sampling mechanism which comprises an underwater robot detecting device, wherein the robot detecting device is connected with a buoy communication device floating on a water surface through a buoy cable; the buoy communication device is connected with a monitoring terminal through a beidou communication satellite; a deploying and retracting line device matched with the buoy cable is arranged in the buoy communication device; the buoy cable comprises a guide line; steel wires are uniformly arranged at the outer side of the guide line; a protective rubber shell is arranged at the outer sides of the steel wires; the buoy cable is adopted to connect the robot detecting device and the buoy communication device, the buoy communication device is connected with a remote terminal through the beidou communication satellite, and a weak electric field is adopted for information transmission, so that the transmission efficiency is greatly improved, the equipment volume is reduced, and the power consumption of communication is greatly reduced.