The invention discloses a fixing mechanism used for crude oil conveying pipeline machining. The fixing mechanism comprises a containing table, a first baffle and a second baffle; multiple blind holes are formed in the two sides of the containing table, fixing elements are arranged in the blind holes, one end of the first baffle and one end of the second baffle are fixed to the side walls of the containing table through the fixing elements, a rotating element is arranged between the other end of the first baffle and the other end of the second baffle, and is inserted in the first baffle and the second baffle in a penetrating manner, the first baffle and the second baffle are provided with movable rods, the movable rods are connected with the first baffle and the second baffle through threads, clamping plates are arranged at the tail ends of the movable rods, a supporting rod is arranged at the bottom of the containing table, a sleeve is arranged at the bottom end of the supporting rod, a base is arranged at the bottom end of the sleeve, and universal wheels are arranged at the bottom of the base. Clamping of petroleum tubular goods with different diameters can be met, meanwhile, the height can be adjusted, use needs of different heights can be met, and it is ensured that the tubular goods can be kept stable in the machining process.