The invention provides a tree-planting machine which comprises a rack (1), a hole digging device and a trailer box (2) pulled by a maneuvering vehicle head; the rack (1) is connected with the front of the trailer box (2) through a four-connecting-rod mechanism (3) and a lifting hydraulic cylinder (4); the hole digging device comprises a twist drill (5), a drill rod (6) of the twist drill (5) is connected with a power mechanism (8) through a belt wheel (7), the belt wheel (7) is rotatably fixed to the rack (1), the twist drill (5) can be driven by a drill lifting hydraulic cylinder (10) to move vertically while rotating, the twist drill (5) below the rack (1) is provided with a backfilling device, and the backfilling device comprises a soil pushing plate (11) and an annular fixing disc (12), an outer tooth ring (13) and an inner tooth ring (14) which are arranged on the periphery of the twist drill (5) in a sleeving mode respectively. The tree-planting machine has the advantages of being reasonable in design, convenient to use and high in work efficiency, can be mounted on a little four-wheeled vehicle or other agricultural vehicles for use and integrates functions of hole digging, backfilling of soil and compressing.