Aimed at the characteristics of internal high pressure forming technique of volume contracted tube parts, a pressure control system for internal high pressure plastic forming in tube is put forward. This system was mainly included of power system, control system and ultra-high pressure water valve and other key components with the realization of overflow function. The overflow of the high pressure water could be realized by the pressure control system within the tube in the process of mold clamping and then controlled the pressure inside the tube, so that the tube could be proceeded with internal high pressure forming at the same time of mold clamping. In addition, combined with the pressure control system and hydraulic extrusion machine, the internal high pressure forming experiment of the DC01 welded tube was carried out. The results of experiment are carried out to verify the performance of the pressure control system to meet the requirements.