The invention relates to a tunnel underground excavation machine, which comprises a vehicle frame (1), wherein an electric control device (2) and a cab (3) are arranged above the vehicle frame; a crawler traveling device (20) is arranged under the vehicle frame (1). The tunnel underground excavation machine is characterized in that a main sleeve (6) ascending and descending in a vertical direction is also arranged on the vehicle frame; an axial line of the main sleeve (6) is arranged along the length direction of the vehicle frame (1); a sub sleeve (7) sliding along the axial direction of the main sleeve (6) is arranged in the main sleeve (6); one end of the sub sleeve (7) is connected with a cutter head frame (11); at least one cutter head driving device (9) is arranged on the cutter head frame (11); a power output shaft of each cutter head driving device is connected with a milling-planing cutter head (10). The tunnel underground excavation machine has the beneficial effects that the structure is simple; the safety is high; the excavation can be performed in the full cross section range of a tunnel; the layered excavation can be performed according to the practical condition of the tunnel; the fully mechanical operation of the tunnel underground excavation construction is realized; the characteristic of wide application range is realized.