Mollusks with infinite degrees of freedom and continuous deformation ability can change their shape and size at will in a large range, and have strong adaptability in nature. Developing bionic soft robots with similar capabilities has always been the goal of researchers all over the world. As a continuation of bionic robot research, bionic soft robot has excellent movement flexibility and compatibility with complex environment through the combination of active deformation and passive deformation, and has broad application prospects in military, scientific research, medical and other fields. Aiming at the problem that the current bionic soft robot has a single movement mode, and the movement efficiency and environmental adaptability cannot be effectively balanced, this paper takes the bionic soft robot which can realize three movement modes as the research object, and studies the realization principle of multiple movement modes of bionic soft robot, the overall structure design of bionic soft robot, the movement characteristics of bionic soft robot and the dynamic characteristics of flat bending actuator embedded with SMA wires around the realization mechanism of three movement modes of bionic soft robot. The main research contents and achievements of this paper are as follows: (1) By analyzing the movement characteristics of various mollusks in nature, on the basis of existing research work, combined with the characteristics of shape memory alloy, a deformable bionic soft robot is designed, which integrates rolling movement, crawling movement and ω-type movement. On the flat road, the bionic soft robot pushes forward through its own flexible deformation, improving the movement speed and efficiency; When passing through a narrow space, the body uses peristalsis to improve the passability; When encountering ravines or obstacles, the body deformation adopts ω-shape forward to improve its obstacle-crossing ability. Through the detailed study of three motion modes of bionic flexible robot, the motion mechanism of flexible robot to realize three motion modes is obtained, and the overall scheme design of flexible robot is completed on this basis. Soft robot adopts modular design idea and consists of moving unit and separating unit. Each movement unit includes a deflection unit and a peristalsis unit, and the deflection unit and the peristalsis unit of the flexible robot and the end-to-end connection structure are designed. (2) Using the multi-rigid-body kinematics simulation software ADAMS, two typical motion modes of bionic soft robot: rolling motion and crawling motion are simulated and analyzed. Based on the pseudo-rigid body model, the rolling simulation model of bionic flexible robot is established in ADAMS. By adjusting the application sequence of spring force, the rolling of the robot is optimized, and the movement displacement and speed curves of the bionic soft robot in the X-axis direction (rolling direction) and the Y-axis direction (perpendicular to the rolling direction) are obtained, and the control strategy of the bionic soft robot rolling motion is given. The simulation model of crawling motion of flexible robot is established in ADAMS, and bionic bristle structure and rough ground are simulated by micro-sawtooth structure. The displacement and velocity curves of the flexible robot in the X-axis direction (crawling direction) are obtained, and its motion characteristics are analyzed.