The invention discloses an internal hydraulic pressing system applied to a robot position changing machine and belongs to the field of automatic equipment. The internal hydraulic pressing system comprises an electric control hydraulic station and oil way mechanism, a large-rotation oil supply rotating device, a vehicle frame hydraulic clamping mechanism and a robot position changing machine 360-degree rotation mechanism. The electric control hydraulic station and oil way mechanism is connected with the large-rotation oil supply rotating device, the vehicle frame hydraulic clamping mechanism and the robot position changing machine 360-degree rotation mechanism through hydraulic pipeline systems correspondingly. The robot position changing machine 360-degree rotation mechanism is connected with the vehicle frame hydraulic clamping mechanism. The electric control hydraulic station and oil way mechanism comprises an electric control box which is used for inducing whether a loading machine front vehicle frame is positioned on a platform or not, and a hydraulic station automatic control device achieving automatic oil supply. By means of the internal hydraulic pressing system applied to the robot position changing machine, the inner portion and the outer portion of a hydraulic loop can complete 360-degree relative rotation rotating and automatic pressing of the loading machine vehicle on the robot position changing machine can be completed, in addition, the structure is simple, the performance is stable, and the internal hydraulic pressing system has the unmanned work application and popularization condition.