The invention relates to a thick-layered polyurea material and a preparation method thereof. The preparation method comprises steps as follows: (1), polyether polyol, a plasticizer and filler are taken and heated to 100-120 DEG C, a mixture is dehydrated under the vacuum condition and is cooled to 75-90 DEG C, polyisocyanate is added, a thermal insulation reaction is performed for 1-2 h, and a reaction product A is obtained; (2), hydroxyl oxazolidine is added to the reaction product A, a mixture is subjected to a reaction at the temperature of 75-90 DEG C for 1-2 h, a reaction product B is obtained, and the thick-layered polyurea material is prepared. The thick-layered polyurea material prepared with the method can be laid for 3 mm or thicker once, and no CO2 is emitted during curing, so that the problem of bubbling is solved; besides, the content of isocyanate groups is low, thus, the harm to a constructor and a user is reduced, and various properties such as viscosity, hardness, toughness and the like are better.