This paper deals with the human-interactive actions of a quadruped robot by using Genetic Algorithm. In case we have to work out the designed plan under the special environments, our robot will be required to have walking capability, and patterns with legs, which are designed like gaits of insect, dog and human. Our quadruped robot (called SERO) is capable of not only the basic actions operated with sensors and actuators but also the various advanced actions including walking trajectories, which are generated by Genetic Algorithm. In this paper, the body and the controller structures are proposed and kinematics analysis are performed. All of the suggested motions of SERO are generated by PC simulation and implemented in real environment successfully.