In this work, improvement of the observation contrast was investigated by using a carbon film as the hard mask for pattern transfer of block copolymer (BCP) nanodots. The PS-PDMS (Poly(styrene-b-dimethyl siloxane)) block copolymer was adopted here. The observation contrast was greatly improved after transferring block copolymer (BCP) nanodots pattern to the underlying Si substrate through the carbon hard mask compared that before nanodot pattern transfer. Pattern transfer was also demonstrated to be very effective using carbon hard mask.