The invention discloses a pressure self-balance ultrahigh pressure seal water swivel. The pressure self-balance ultrahigh pressure seal water swivel comprises a mandrel, a water swivel shell, a gland,a pressing wire, a transition pressing disc, rotating bearings, and a thrust ball bearing. The mandrel penetrates through the gland, the bearings, the transition pressing disc and the pressing wire to be arranged in the water swivel shell, the rotating bearings are arranged on the two sides of a shoulder of the mandrel to enable the mandrel to be supported in the water swivel shell, the transition pressing disc achieves the transition effect of converting two bearing stress directions to axial direction from radial direction between the rotating bearings and the thrust ball bearing, the gland is arranged on the right end of the water swivel shell, a seal part is arranged between an end cover and the mandrel, a seal part is arranged between the end cover and the water swivel shell, a water passing hole is formed in the mandrel, and communicates with a water draining hole in the left end of the water swivel shell, a high-pressure seal part is arranged at the fit position of the left end in the water swivel shell and the mandrel, the interior of the mandrel is isolated from the high-pressure water led by the water swivel to achieve the seal effect, and a thread matched with the drill rod is arranged on the left end of the water swivel shell. The water swivel can be connected with the drill rod, the mandrel is not moved along with rotation of the drill rod, large pressure can beborne, and the advantages of being convenient to connect, wear-resisting and good in seal can be achieved.