The invention provides a composite anti-heat structure of a large carrier rocket cabin body. The structure comprises a low-density softwood layer, a high-density softwood layer and a fire-resistant ceramic fiber layer, wherein the low-density softwood layer is connected with the rocket cabin body in a pasting mode; the high-density softwood layer is connected with the low-density softwood layer ina pasting mode; the fire-resistant ceramic fiber layer is connected with the high-density softwood layer in a pasting mode; and a spliced surface of the fire-resistant ceramic fiber layer is connected with the rocket cabin body through bolts. According to the composite anti-heat structure of the large carrier rocket cabin body, the three kinds of anti-heat materials with different anti-heat performance and density are compounded, the problem of thermal environment protection of thousands of DEG C on the large carrier rocket cabin body is solved, and meanwhile, the requirements of light weightand low cost of the anti-heat structure are met.