The invention discloses an energy-saving and environment-friendly pit digging device for tree planting. An upper cover is mounted at the top end of a box, a control panel is arranged at the head end of the box, a frequency decreasing button, a frequency increasing button and a switch are arranged on the control panel, the switch is arranged between the frequency decreasing button and the frequencyincreasing button, the frequency increasing button is arranged on the left side of the switch, a support plate is mounted on the lower surface of the box, four bases are mounted at four corners of the support plate, moving wheels are mounted on the bases, a partition board is arranged in the box, a power supply chamber is formed in the upper end of the partition board, a storage battery is mounted in the power supply chamber, a work chamber is formed in the lower end of the partition board, and a motor is mounted in the work chamber and fixed on a support. The pit digging device has the characteristics of one-time pit forming, low electric energy cost and small pollution.