Underground drill string vibration reducing and pressurizing device

The utility model relates to an underground drill string vibration reducing and pressurizing device, which is a matching tool in oil and natural gas drilling operation, and comprises an upper conversion joint, a spring, a center shaft, a piston shaft, a locking nut, a water inlet valve, a seal assembly, a pressurizing cylinder, a pressurizing cylinder centralizing barrel, a pressurizing cylinder outer barrel, a water outlet valve, a high-pressure flow passage and a lower conversion joint. In drilling-in process, when a drill string longitudinally vibrates, the drill string drives the conversion joints, a spring upper plugging joint, the center shaft and the piston shaft to move up and down together relatively to the pressurizing cylinder; and drilling liquid is sucked and compressed into the pressurizing cylinder. When power is transmitted and the drilling liquid is circulated, energy generated by vibration of the drill string can be absorbed simultaneously, vibration energy of the drill string can be converted into pressure energy of the drilling liquid to realize well bottom pressurizing of the drilling liquid. The underground drill string vibration reducing and pressurizing device can reduce vibration of the drill string, and protect the drill string, and increases jet pressure and improves rock breaking efficiency.