An eight-legged bionic robot with a tail launcher was designed by combining the advantages of robotic octopods and the spider bionic principle. Build 3D models with Solidworks, design a set of eight feet of straight and turn-in-place gait, and simplify gait angle control. By developing an improved D-H method kinematic model for the leg structure, performing joint space trajectory planning, and differential motion velocity analysis. Capturing real spider gait data with high-speed industrial cameras, combining motion models and capture data to verify the feasibility of gait angle control by drawing images using Matlab. When the physical prototype verification of the robot was conducted, the feasibility of the gait angle design was fully demonstrated.