The invention discloses a general and portable welding clamp which comprises an operating table, positioning columns, positioning blocks, clamping blocks and a base plate. The general and portable welding clamp is characterized in that pad blocks and fixing blocks are arranged on the operating table, one end of each positioning column is arranged in the corresponding fixing block, each positioning block is arranged on the corresponding positioning column through a fastening bolt, a connecting rod is arranged on the corresponding positioning block, the clamping blocks are arranged on the connecting rods through installing blocks, adjusting screws are arranged on the base plate, and one end of each adjusting screw is arranged in the corresponding pad block. The positioning blocks are arranged on the positioning columns through the fastening bolts so that the positioning blocks can rotate on the positioning columns. The clamp is suitable for workpieces different in shape, the universality of the welding clamp is improved, the clamping blocks are arranged on the connecting rods through the installing blocks and are arranged to be of replaceable structures, the stability of each workpiece between the clamping blocks is improved, the application range of the welding clamp can be also improved, and the manufacturing costs of multiple welding clamps are reduced.