The invention discloses a welding device and belongs to the field of petroleum. The welding device comprises a circular tubular fixing barrel, wherein a circular tubular straightening barrel is weldedto the lower end of the fixing barrel; a plurality of first holes are formed in the fixing barrel; a second hole is formed in the upper end of the straightening barrel; a plurality of third holes areformed in the lower end of the straightening barrel; a plurality of fixing nuts are welded to the outer side of the fixing barrel and correspond to the positions of the first holes; a plurality of straightening nuts are welded to the outer side of the straightening barrel and correspond to the positions of the third holes; fixing screw rods being in screwed connection with the fixing nuts are arranged in the first holes; and straightening screw rods being in screwed connection with the straightening nuts are arranged in the third holes. According to the welding device disclosed by the invention, the fixing screw rods positioned on the fixing barrel are tightened, and then the straightening screw rods positioned on the straightening barrel below the fixing barrel are adjusted, thereby ensuring that to-be-welded oblique pipelines at upper and lower positions can correspond to each other, and the firmer and more convenient welding operation can be achieved.