The invention discloses a cement-polyurethane composite mine filling material and a preparation method thereof. The cement-polyurethane composite mine filling material comprises a component A and a component B, wherein the component A is prepared from the following components in parts by weight: 5 to 30 parts of cement, 50 to 75 parts of isocyanate, 100 to 125 parts of polyether polyols, 1 to 5 parts of catalyst, 0.5 to 3 parts of surfactants and 0.5 to 10 parts of additives; and the component B is 0.5 to 5 parts of foaming agent, thus obtaining the mine filling material. The two components are mixed according to a ratio of 100: 5 and sufficiently foamed on a fabric under a natural condition. In the preparation process of the mine filling material, the released carbon dioxide and partial heat do not generate toxic and harmful substances causing the environmental pollution; the prepared mine filling material is good in adhesion performance can be closely bonded with a coal layer of a mine; and according to different filling conditions, different mine filling materials of different performance can be prepared by adjusting the ratio of raw materials. The entire construction process is simple in operation. The requirement on equipment and operation personnel is not high.