The invention discloses a building cutting machine capable of conducting conversion cutting on the wall surface and the ground. The building cutting machine comprises a main handle and a protection shell. A cutting blade is mounted on the inner side of the protection shell, and the outer side of the protection shell is provided with a scale line, a positioning plate and sliding grooves; the positioning plate is arranged on the sliding grooves, and the scale line is arranged in the middle of the positioning plate; a water-spraying electromagnetic valve is fixed to the upper side of the protection shell, and the outer side of the water-spraying electromagnetic valve is connected with a water-guiding hose; and a main moving rod and an auxiliary moving rod are connected through a connecting bottom plate, and fastening bolts are mounted on the connecting bottom plate. According to the building cutting machine capable of conducting conversion cutting on the wall surface and the ground, corresponding adjusting work can be conducted on different working faces of a building, and accordingly, cutting work on the different working faces of the building is completed; and the size of cutting work can further be controlled effectively in the cutting process, and thus the cutting work error of the device is reduced effectively.