The invention relates to the technical field of composite materials, and particularly relates to an organic-inorganic hybrid composite material and a preparation method thereof. The composite materialis prepared by mixing a first component which is polyisocyanate or modified polyisocyanate and a second component which is a metallic salt solution or a metalloid salt solution based on the mass ratio of 10: 1-1: 5. The preparation method of the composite material comprises the following steps: 1) preparing the first component which is polyisocyanate based on the abovementioned ratio for later use; 2) dissolving the metallic salt solution or the metalloid salt solution to regulate the solution concentration to be 20-90% by mass of the second component, and performing standing for later use; and 3) adding the first component to the second component based on the component ratio of 10: 1-1: 5; fully mixing; and curing for 24h under the temperature of 25+/-3 DEG C and the humidity of 50%+/-10to obtain the organic-inorganic hybrid composite material. The prepared organic-inorganic hybrid composite material is uniform in organic-inorganic distribution, and dense in structure; the inorganiccomponent size reaches nanometer grade; the metallic salt solution or the metalloid salt solution replaces alkali metal silicate to produce a novel inorganic component; the strength is high; the modulus is high; the high temperature is resistant; the corrosion is resistant; the mechanical performance is high; the reaction rate is high; and the cost is low.