This invention discloses a composite building construction and a method for building it. The construction comprises the base, hollow frame units and the building parts, wherein each hollow frame unit is cube formed from four bridging beams in the topping, four studs in the middle and four bridging beams in the lower, and the hollow frame units are connected with each other which form the space outline of the construction, by which the whole construction has a outline structure without wallboard; the building parts include wall, floor, door, window, roof, theft against wet, feed water equipment, pumping appliance and electrical apparatus, and each building part is matched with the space outline and set inside the outline of the frame.