The invention discloses a building firefighting and extinguishing robot. The building firefighting and extinguishing robot comprises travelling parts, a water suction part, a water spraying part and firefighting mechanical arm parts and is characterized in that when water leakage is detected by water leakage detectors, second hydraulic cylinders of the water suction part drive first telescopic rods to extend towards the ground, thus water suction pipes of the first telescopic rods get close to the ground to suck water through first water suction pumps, and after a water collection tank is fullof water, the water is drained to a connected sewer pipeline through a drainage opening; and when fire alarming is detected by a firefighting alarm box, first hydraulic cylinders of the travelling parts retract, then first motors drive synchronous belt pulleys to the designated position of the fire, the water is sucked from the water collection tank by second water suction pumps of the water spraying part, the water is sprayed by spray heads, and when no water is in the water collection tank, the firefighting mechanical arm parts lock the positions of the firefighting spray heads through coordination work of radars and cameras. The building firefighting and extinguishing robot automatically detects the fire and water leakage, and the unnecessary loss is reduced and avoided.