A waist structure includes: a support assembly located between a trunk structure and two leg structures; a waist servo mounted on the support assembly and two first-stage leg servos; and a transmission member connected between the waist servo and the first-stage leg servos. The waist servo connects the trunk structure to the support assembly, and the first-stage leg servos connect the support assembly to the leg structures. The waist servo includes an output shaft connected to the transmission member. Each first-stage leg servo has a connecting end. The transmission member includes a first connecting member and a second connecting member securely mounted on the connecting ends, the first transmission member mounted on the output shaft and connected to the first connecting member, and the second transmission member which is driven by the first transmission member connects to the second connecting member.