Dry powder of plastering mortar and preparation method of plastering mortar

The invention relates to dry powder of plastering mortar and a preparation method of the plastering mortar. The dry powder of the plastering mortar comprises the following components: 80-120 kg of cement, 800-820 kg of sand, 60-80 kg of an admixture and 15-25 kg of additives, wherein the additives comprise hydroxypropyl methyl cellulose ether, sodium alpha-olefin sulfonate and dodecyl laurinol, the addition amount of the hydroxypropyl methyl cellulose ether is 0.2 kg, and the total addition amount of the sodium alpha-olefin sulfonate and the dodecyl laurinol is 0-4/50 of the addition amount ofthe hydroxypropyl methyl cellulose ether. The preparation method of the plastering mortar comprises the following steps: stirring the dry powder of the plastering mortar, slowly adding purified waterin the process of stirring, and uniformly mixing the dry powder of the plastering mortar with purified water to obtain the plastering mortar, wherein the total addition amount of the purified water is 15% of the total amount