The influence of admixtures(aluminum sulfate, alum, gypsum) on properties of traditional sticky rice lime mortar and its scientific mechanism was studied by means of SEM and XRD. Results indicate that addition of aluminum sulfate improves the mechanical property, freeze thaw resistance and water resistance of sticky rice lime mortar significantly. Whereas the addition of alum mostly improves the mechanical property of sticky rice lime mortar. Gypsum has few contribution to improvement of mechanical property and weather resistance of sticky rice lime mortar. All of these three admixtures have favorable effect on slowing down and reducing the shrink of sticky rice lime mortar. Aluminum sulfate should be used as admixtures for sticky rice lime mortar in conservation of cultural relics.