Abstract: For a better application of differential mechanism to rocker-type mobile robot,this paper analyzes the functions and characteristics of differential mechanism for rocker-type mobile robot,which keeps the robot body at an average angle between the two rockers.Six gear-type differential mechanisms are proposed,including the types of ZUWGW,NW,DW, WW and NGWW 2K-H planetary gear differential mechanisms and a differential mechanism consisting of two NGW 2K-H planetary gear mechanisms.The operating principle and characteristics of each differential mechanism are analyzed,their realization conditions are deduced,and the detailed mechanical structure designs of a ZUWGW type bevel gear differential mechanism and a NGWW type planetary gear differential mechanism are given.