For transversely isotropic rocks such as schist, shale, etc, a method to determine the anisotropic elastic constants was proposed. Theoretically, equations of elastic constants E1, E2, and G2 can be derived from the measured strains in arbitrary three directions. If we attach three strain gages in accordance with the directons of anisotropy on the rock specimen under uni-axial compression, anisotropic elastic constants can be determined by these equations. With this method, the degree of anisotropy of transversely isotropic rocks will be easily evaluated by simple laboratory test.