Abstract: Based on bio-observation and analysis on natural crabs,a crab-like robot's prototype is developed.An alternating equal-phase wave gait for crab-like robot is presented by analyzing crabs' motion with event sequence method.Based on 2n-legged wave gait,the 8 legs are alternately divided into 2 groups,and the legs' phases in the same group are distributed uniformly within a circle by adjusting the phase factor of the successive legs within a tetrapod group in order to reduce energy consumption of the robot.The gait test results of the crab-like prototype show that the alternating equal-phase wave gait accords with motion characteristics of crabs,and the robot can walk smoothly and receive more favorable gait stability and smaller driving power fluctuation than the double tetrapod one.