Fabricated building steel structure welding tool

The utility model relates to the field of welding tools, in particular to an assembly type building steel structure welding tool which comprises a bearing plate. A movable feeding assembly used for movable feeding is arranged at the upper end of the bearing plate. The L-shaped block is pushed to the left end of the check block, so that the L-shaped block can be rapidly moved and positioned, then a supporting piece to be welded is manually placed on the right-angle inner wall of the L-shaped block, the seventh electric cylinder is started firstly to enable the pressing block to move downwards, the supporting piece is pressed downwards and fixed to the L-shaped block, and then the L-shaped block is fixed to the right-angle inner wall of the L-shaped block. Then a sixth electric cylinder is started to enable a fixing sleeve block to move backwards, the fixing sleeve block drives a movable column to move backwards and drives a connecting column to move backwards, a welding rod is placed in a gap where a supportin