The invention provides a preparing method of a carbon fiber composite thin-wall curve pipe. The method comprises the following steps that firstly, a foam core die is placed in an air bag, and the air bag is vacuumized through a vacuum pump till the foam core die is closely wrapped by the air bag; secondly, the air bag is evenly wrapped by prepreg; and thirdly, the prepreg is placed in a steel outer die, the steel outer die is placed in an oven to be heated, in the heating process, the air bag is inflated with compressed air through an air compressor, the prepreg is cured, deflation and die stripping are carried out after curing is finished, and the carbon fiber composite thin-wall curve pipe is obtained. The inner shape face of a product is controlled through the foam core die, the outer shape face of the product is controlled through the steel outer die, and the product has the beneficial effects that the appearance of the product is high in controllability, the surface state is smooth and clean, the mechanical performance is good, and the product is simple and economical; and the preparing method is suitable for forming of curve pipe products with the continuous length and large size.