The Mg₁₇Al₁₂ (110) surface has five possible terminations (T1-T5). The T3 termination has been regarded as the most stable termination for long time, whereas recent theoretical calculations have revealed that the T1 termination is the most stable one. To solve the dispute, density functional theory calculations were performed in this study to unravel the most stable termination of Mg₁₇Al₁₂ (110) surface. Surface energy calculation results show that, whether defects are considered or not, the T1 termination is always the most stable termination of Mg₁₇Al₁₂ (110) surface. The stability of T1 termination may be ascribed to the Al truncated-tetrahedron because only cutting Mg₁₇Al₁₂ along T1 termination of (110) surface will not destroy the integrity of Al truncated-tetrahedron. In addition to unraveling the most stable termination, work functions of Mg₁₇Al₁₂ (110) surface were also calculated. The results show that the work function of Mg₁₇Al₁₂ (110) surface is mainly controlled by concentration of surface Al_Mg defects.