The invention provides a building construction machine with loading and unloading functions. The building construction machine comprises a mixing barrel, a mixing cavity, supporting columns, reinforcing rods, connecting bases, a first motor, a coupler, a connecting shaft, stirring blades, a discharge head, a flap valve, a movable box structure, a conveying frame structure, a dustproof barrel structure, a water storage tank structure and a lower sliding block. The mixing cavity is formed in the upper portion in the mixing barrel. The supporting columns are in threaded connection to the left side and the right side of the lower surface of the mixing cavity, the connecting bases are mounted on the middle right side of the upper surface of the mixing barrel through bolts, and meanwhile the first motor is mounted between the connecting bases. The building construction machine has the advantages that by means of the movable box structure, supporting strips can be conveniently moved, meanwhile, a storage box is also conveniently moved, then cement in the storage box is more conveniently conveyed into a trolley, and the problem that the cement can be conveyed by workers only with tools such as a shovel is avoided.