In this paper, a lightweight and interactive rat-like quadruped robot is designed. The mechanical structure design, hardware and software design, motion posture calculation are carried out. In terms of mechanical structure design, the legs and trunk of the mechanical mechanism were designed by imitating the skeleton of the rat. Each joint used a steering gear, and then modified and simplified from the balance and movement characteristics of the rat. In terms of software and hardware design, each steering gear can be controlled separately, and there are also combined algorithms to transform some behaviors of rat into instincts through algorithms. In the system, there are Raspberry PI and Arduino, the upper computer used for communication and calculation, while the lower computer used to ensure basic work and make rules. Finally, the bionic robot rat can be made to stand, climb and jump by remote control, host computer or personal computer, but also bionic robot rat can directly receive signals. At the same time, the posture algorithm also reasonably calculated the motion posture.