The invention discloses an automatic tree planter. The automatic tree planter comprises a car board, wheels installed on the lower surface of the car board, a rotary digging device which is installedon the car board and located on the middle portion of the front end, in a moving direction of the car board, of the car board, a tree planting device which is installed on the car board and located atthe rear of the rotary digging device, and transporting device which are installed on the car board and symmetrically arranged on two sides of the tree planting device, wherein a receding opening isformed in an end portion, in the moving direction of the car board, of the car board, the rotary digging device is arranged above the receding opening, and a planting opening, which communicates withthe rear end of the car board, is formed in the portion, located at the rear of the tree planting device, on the car board; and the tree planting device comprises a second hydraulic cylinder and a rectangular supporting board, the supporting board is arranged at the rear of the rotary digging device in a length direction of the car board, the end, away from the rotary digging device, of a tray ishinged to the upper surface of the car board, the second hydraulic cylinder is arranged between the supporting board and the car board, a piston rod end portion of the second hydraulic cylinder is hinged to the supporting board, and a cylinder body end portion of the second hydraulic cylinder is hinged to the car board. The automatic tree planter has the advantages that labor force is saved, the labor intensity of farmers is reduced, and the tree planting efficiency is improved.