Ready-mixed mortar thickening plasticity-maintaining agent

The invention relates to ready-mixed mortar thickening plasticity-maintaining agent, which belongs to the field of building material. The ready-mixed mortar thickening plasticity-maintaining agent is characterized in that: the agent is formed by mixed raw materials including modified sodium bentonite, hydroxypropyl methyl cellulose ether, phosphorus slag powder and polycarboxylate superplasticizer; the mass shares of the raw materials are as follows: 20-35 shares of the modified sodium bentonite, 0.40-0.60 share of the hydroxypropyl methyl cellulose ether, 100-200 shares of the phosphorus slag powder, and 3.0-5.0 shares of the polycarboxylate superplasticizer. The invention has the advantages of performance for improving mortar, simple preparation, convenient use, is suitable for masonry mortar, plastering mortar and surface mortar.