The invention discloses a pipe welding fixture quick in clamping. The pipe welding fixture quick in clamping comprises a bottom plate, a supporting base A, a supporting base B, infrared generators, an infrared ray induction plate and hydraulic bearings. A tenon-shaped groove is formed in the upper surface of the bottom plate in the horizontal direction. The supporting base A and the supporting base B are arranged at the two ends of the tenon-shaped groove and are connected with an air cylinder A and an air cylinder B through connection rods. The front side of the bottom plate is provided with the multiple sets of infrared generators, and the rear side of the bottom plate is provided with the infrared ray induction plate. The supporting base A and the supporting base B are the same in structure. The supporting base A comprises the hydraulic bearing, an upper arc-shaped clamping block and a lower arc-shaped clamping block. A trapezoid groove is formed in the outer surface of an inner ring of each hydraulic bearing. The two ends of each trapezoid groove are provided with sealing devices. Each sealing device is internally provided with an oil inlet channel and an oil outlet channel. The outer sides of the sealing device are provided with the upper arc-shaped clamping blocks and the lower arc-shaped clamping blocks. The pipe welding fixture quick in clamping has the beneficial effects of being quick in clamping, automatic in aligning and rolling and high in working efficiency.