The invention provides a playground lawn anti-freezing agent and a preparation method thereof, and mainly aims at solving the problem that a ryegrass lawn in North China is difficult to live through the winter, becomes withered and yellow in winter and the like, and is capable of deferring the withering and yellowing and dormancy of the lawn and promoting the lawn to turn green and grow in advance, and thus effectively prolonging the green period of the lawn. The playground lawn anti-freezing agent comprises the following components: 10-15% of high-fat membrane emulsion, 12-18% of nutritional agent, 0.8-1.6% of rare earth element, 3-5% of water-retaining and anti-freezing agent, 1-1.5% of growth regulator, 0.5-1% of penetrating agent, 0.2%-0.5% of calcium chloride or calcium nitrate, and 60-70% of distilled water. A compound technical formula is adopted; the high-fat membrane emulsion in the formula is capable of forming a layer of air permeable thin film on the leaf surface of the lawn so that the water retention capacity of the lawn is improved, heat loss is avoided and harm caused by low temperatures to the lawn is effectively reduced; meanwhile, the nutritional agent, rare earth elements and the water-retaining and anti-freezing agent are added, and the penetrating agent is blended with the mixture. After the playground lawn anti-freezing agent is sprayed to the lawn, the permeability and the stability of the cell membranes of the lawn can be maintained, the contents of soluble sugar and free amino acids in cells can be quickly increased, and the heat storage capacity of cells is improved. The playground lawn anti-freezing agent has a physical anti-freezing effect and physiological anti-freezing effect.