The guiding screen tube is an important part of the ultra-short radius horizontal well flexible drilling tool, and the rationality of the structure size directly affects the drilling ability of the drilling tool. Based on the condition that the guiding screen tube matches the borehole curvature, the maximum length of a single section of the guiding screen tube was obtained by fitting the motion trajectory equation of the guide screen tube with Bezier curve. The structural parameters were optimized based on the strength and bending stiffness conditions. The finite element model of the guiding screen tube was established by using the finite element method and considering the material nonlinearity of the guiding screen tube and the contact nonlinearity between the transverse joints, and the solving strategy of finite element model was given. The rationality of the structure optimization design of guiding screen tube was verified through the mechanical analysis of the optimized single section guiding screen tube. The research results provide reference for the design of slotted structure of guiding screen tube.