Abstract Double arc gear has higher teeth surface contact intensity and gear teeth bending strength than involute gear but its geometry design and mechanics computation are quite complex. To promote this highperformance gear, design and computation automation have to be realized. For this purpose, DAM software is developed based on OpenGL graph kernel. It integrates geometry design, mechanics computation and generation of CNC machining code together. Due to length limitation, this paper only described the part of solid geometrical design process.