Abstract: An option card-equipping device for improving electromagnetic shielding and a computer using the same includes a bracket of an option card and a shielding projection part. The bracket is connected to the option card. The shielding projection part shields electromagnetic interference between the bracket of the option card and a chassis of a main board, when the bracket of the option card is fixed on the chassis of the main board, the projection part being disposed on the chassis of the main board. By firmly connecting the bracket and the chassis of a main board and making the shielding projection part in order to prevent an empty space from occurring and thereby prevent high frequency signals from flowing out, electromagnetic interference can be eliminated.