An aircraft model was tested in spin tunnel to investigate the effect of C.G. (center of gravity) location in longitudinal direction on aircraft spin characteristics. The results show that the more obvious the model rotates, the more critical spin situation gets under forward C.G. condition. Meanwhile, the effect of C.G. location in longitudinal direction on spin characteristics of canard aircraft and hightail aircraft are also presented, compared and analyzed. Furthermore, the effect of C.G. location in lateral direction on general aircraft spins characteristics was also investigated in spin tunnel tests.