A composite brake disc, comprising a brake disc hat and a friction ring mounted on the brake disc hat, wherein the composite brake disc further comprises a plurality of composite brake disc connecting assemblies, and the friction ring is connected to the brake disc hat by the plurality of composite brake disc connecting assemblies; each of the plurality of composite brake disc connecting assemblies comprising a sleeve and a spring member; wherein the sleeve comprises an upper pressing plate, a lower pressing plate and a connecting column connecting the upper pressing plate and the lower pressing plate; the connecting column is provided with a connecting hole, and a pair of U-shaped clamping slots are formed between the upper pressing plate, the lower pressing plate and the connecting column; and the spring member comprises a pair of elastic pieces cooperating with the pair of U-shaped clamping slots and a connecting bridge connecting the pair of elastic pieces; the brake disc hat comprises a hat brim, a plurality of disc hat notches for mounting the spring members are uniformly distributed in a circumferential direction of an outer edge of the hat brim, disc hat steps are provided between adjacent disc hat notches of the plurality of disc hat notches, the elastic pieces of the composite brake disc connecting assemblies are snap-fitted onto the disc hat steps, the lower pressing plates of the composite brake disc connecting assemblies are provided between the brake disc hat and the friction ring, an inner ring is provided inside the friction ring, mounting holes cooperating with the disc hat notches are uniformly distributed on the inner ring, the connecting columns of the composite brake disc connecting assemblies are inserted into the mounting holes, and the friction ring and the brake disc hat are connected by fasteners inserted into the connecting holes; characterized in that, an upper surface and a lower surface of each disc hat step are respectively provided with an upper groove and a lower groove for positioning the upper elastic piece portion and the lower elastic piece portion. each of the plurality of composite brake disc connecting assemblies comprising a sleeve and a spring member; wherein the sleeve comprises an upper pressing plate, a lower pressing plate and a connecting column connecting the upper pressing plate and the lower pressing plate; the connecting column is provided with a connecting hole, and a pair of U-shaped clamping slots are formed between the upper pressing plate, the lower pressing plate and the connecting column; and the spring member comprises a pair of elastic pieces cooperating with the pair of U-shaped clamping slots and a connecting bridge connecting the pair of elastic pieces; the brake disc hat comprises a hat brim, a plurality of disc hat notches for mounting the spring members are uniformly distributed in a circumferential direction of an outer edge of the hat brim, disc hat steps are provided between adjacent disc hat notches of the plurality of disc hat notches, the elastic pieces of the composite brake disc connecting assemblies are snap-fitted onto the disc hat steps, the lower pressing plates of the composite brake disc connecting assemblies are provided between the brake disc hat and the friction ring, an inner ring is provided inside the friction ring, mounting holes cooperating with the disc hat notches are uniformly distributed on the inner ring, the connecting columns of the composite brake disc connecting assemblies are inserted into the mounting holes, and the friction ring and the brake disc hat are connected by fasteners inserted into the connecting holes; characterized in that, an upper surface and a lower surface of each disc hat step are respectively provided with an upper groove and a lower groove for positioning the upper elastic piece portion and the lower elastic piece portion.