Based on the analysis of the structural characteristics of a small plastic sliding button, a four-cavity injection mold was designed with a inclined guide pillar side core-pulling structure. The cavities were balanced arrangement. Cooling water pipes were arranged on both the fixed and moving die sides. Moldflow simulation was utilized to analyze the molding process in the sequence of 'cooling+filling+holding+warping' using 3D mesh. The results showed that the four cavities were evenly filled, with a filling time of 0.489 0 s. The overall volume shrinkage rate was relatively small, with a maximum of about 3.7% at the side gate. There were fewer air pockets, and the mold parting surface and fitting gap could be used for exhaust. The fusion line and the process combination line basically overlapped. The temperature difference between the inlet and outlet of the cooling medium was 0.13 ℃. The maximum warpage deformation of the plastic part was 0.046 1 mm. Finally, based on the simulation analysis results, a relatively reasonable two-plate injection mold structure was designed.