The invention discloses a crawler crane, comprising a main engine (8), a main arm (7) in pin connection with the main engine (8) and a fixed assistant arm (1) in pin connection with the main arm (7), wherein one end of a fixed assistant arm brace (3) is in pin connection with the junctional part of the fixed assistant arm (1) and the main arm (7); the upper end of the fixed assistant arm (1) and the other end of the fixed assistant arm brace (3) are in pin connection with a fixed assistant arm pulling-forward plate (2); the upper end of the main arm (7) and one end of a mast (9) are in pin connection with a main arm pulling plate (6); and the other end of the mast (6) is in pin connection with the main engine (8). The invention is characterized in that a fixed assistant arm pulling-backward plate (4) is pin connection on the position which is between the junctional part of the fixed assistant arm pulling-forward plate (2) and the fixed assistant arm brace (3) and the main arm pulling plate (6). Compared with the prior art, the invention has the advantages of large arm length and huge hoisting capacity, improves hoisting capacity and lowers usage cost on the condition of the same arm length.