The invention provides a waist joint device. The waist joint device comprises a waist joint member (1), the waist joint member (1) comprises a rotating shaft (11), a first input bevel gear (12) and a second input bevel gear (13), the first input bevel gear (12) and the second input bevel gear (13) sleeve the rotating shaft (11) in a rotatable manner, and the first input bevel gear (12) is opposite to the second input bevel gear (13). The waist joint member (1) also comprises an output bevel gear (14) which is in mesh connection with the first input bevel gear (12) and the second input bevel gear (13), and is used for being fixed with a trunk part in order to be driven by the first input bevel gear (12) and the second input bevel gear (13), and drives the trunk part to carry out rotation and/or pitching motion. The waist joint device is simple in structure, and is practical and feasible.