The invention relates to a trihedral static pressure closed type guide rail self-driven type round rotary table which consists of a base, a supporting mass, a rotary table and a motor. The base is a platform provided with a hole in the middle, the supporting mass is fixedly arranged on the upper part of the platform. The supporting mass is a cylinder of which the center is provided with a throughhole and the upper external surface is provided with a lug boss. The rotary table is arranged on the lug boss of the supporting mass to match with the lug boss. The internal surface of the rotary table is matched with the upper surface, the lower surface and the external circle surface of the boss of the supporting mass in a trihedral way. The center of the internal surface of the top part of therotary table is provided with a principal axis. Static pressure oil cavities are arranged on the matched surfaces of the supporting mass and the rotary table to form a static pressure guide rail. Therotary table has small friction resistance, high accuracy, good rigidity and large carrying capacity.