In this paper, U-shaped components of carbon fiber composite with two different-height flange slabs are studied. Autoclave moulding process and VARIM process are used to prepare the U-shaped components. The U-shaped component angular contraction conditions are studied by measuring their angle. And based on the measurement results, the mould compensation angle is optimized and redesigned. The angular contraction conditions of the U-shaped components made by the two above-mentioned processes are different. When designing the compensation angle of the U-shaped component mould, it is impossible to generalize all the moulds used in different molding processes and we should treat them differently according to the molding process characteristics. In addition, for the U-shaped components with two differentheight flange slabs, whichever kind of molding process they are made by, the degree of angular contraction on the high flange slab side is smaller than that of on the lower flange slab side. When designing the compensation angle of the U-shaped component mould, this distinction should not be neglected.