A tentative fabrication test for thin astronomical mirror has been done. In the test, the active support system is used. The mirror is a meniscus spherical mirror and its parameters are as follows: the diameter is 1035 mm, radius of curvature is 3220 mm, and aspect ratio is close to 40. During the processing, the mirror was supported by 55 supporting points in its back surface. The positions of supporting points and the magnitude of supporting force supplied by force actuators were analyzed by using finite element analysis software. In all of 55 supporting points, 3 points are fixed and the rest are active support which is linked with force actuator. The low-frequency error on the mirror can be corrected when the forces of actuators were adjusted. Finally root mean square (RMS) of surface accuracy error is less than 0.0465λ, RMS of high-frequency error is less than 0.0435λ. It is demonstrated that the technique is suited for fabrication of astronomical thin mirror.