The strong acid and salt composite groundwater in Guizhou province is simulated in the lab, and the influence of single addition and composite addition of mineral admixtures such as fly ash, slag and silica fume etc. on corrosion resistances of cement mortar using the evaluation indexes such as anti-corrosion coefficient, mass change fraction and chloride ion relative diffusion coefficient in the simulated solution is systematically studied. And its anti-corrosion mechanism of cement mortar is discussed. The results show that the single or composite addition of mineral admixtures results in the improvement of anti-corrosion coefficient, the reduction of chloride ion relative diffusion coefficient and the increase of mass change fraction of mortar compared with the control mortar. The three proposed evaluation indexes can evaluate the corrosion resistance of cement mortar exposed to strong acid and salt composite groundwater from different perspectives.