The invention relates to a large-span awning for a construction site. The large-span awning comprises a building, a protective scaffold, end hook pieces and a tarpaulin. The protective scaffold is arranged outside the building; the protective scaffold is connected with end horizontal hanging rods; the end hook pieces are arranged outside the end horizontal hanging rods; the upper portions of the end hook pieces are connected with a main longitudinal rod which is connected with transverse rods; inclined rods are connected to the main longitudinal rod and the transverse rods; the tarpaulin is arranged on the top faces of the main longitudinal rod, the transverse rods and the inclined rods; auxiliary supporting devices are arranged on the transverse rods; and the end horizontal hanging rods are connected with the end hook pieces through end locking devices. The large-span awning is reasonable in design, the occupied site plane area of the construction site is decreased, the stability andbalance of the awning structure are maintained, mounting is quick and convenient, and the rain shading function is achieved.