Rotary joint and oil cylinder

The utility model provides a rotary joint and an oil cylinder, and relates to the technical field of machine equipment joints, the rotary joint provided by the utility model comprises a rotary body and a main shaft, the rotary body is provided with a first oil hole and a through hole, the through hole is vertically connected with the first oil hole, and the through hole is vertically connected with the main shaft from the axis of the first oil hole to two ends of the through hole. A sealing ring, a bearing and a check ring for a hole are sequentially arranged in the through hole, the rotating body is sleeved outside the main shaft through the through hole, the sealing ring, the bearing and the check ring for the hole are sleeved outside the main shaft, the main shaft is provided with a second oil hole, and the second oil hole is communicated with the first oil hole. The rotary joint solves the technical problems that in the prior art, a rotary joint leaks oil easily, and a shaft and a sleeve are separated eas