The invention provides an alkaline activity inhibition material based on active sandstone aggregate and a preparation method of the alkaline activity inhibition material. By adopting the sandstone aggregate with potential alkaline activity, sandstone powder with the specific surface area of (645 to 950) m<2>/kg is prepared through twice grinding of a vertical mill and a ball mill, and the sandstone powder is uniformly mixed with medium heat cement and nano SiO2 in a certain proportion. The inhibition material is prepared from the following raw materials in percentages by weight: 75% to 87% of the medium heat cement, 10% to 20% of the sandstone powder and 3% to 5% of the nano SiO2. The alkaline activity inhibition material prepared in the invention has the technical advantages that the raw materials are easy to get, the machinability is good, the preparation technology is simple, the alkaline activity inhibition effect is obvious, and the preparation process is free of pollution to the environment, and is beneficial to large-scale production and application of engineering.