In order to meet the requirement of convex surface mask in concave surface lithography, convex surface laser direct writing system was set up to fabricate the mask. This apparatus supported up to ±20° tilt angle. With the exposure correction algorithm in the process, the system accomplished writing rectangular grid pattern on a spherical substrate with 50 mm caliber and 51.64 mm radius. It was able to draw circular ring pattern on the surface by result of simultaneous motion of two tilting tables. The experiment shows that this setup has the capacity to fabricate the convex mesh lithographic mask and lay a solid base for convex surface lithography technology.