Threshold signature is an important digital signature in modern electronic commerce. Based on a deformed signature scheme of Hess signature, an effective ID-based threshold digital signature scheme is proposed. In order to improve the security of the scheme, the proposed scheme uses Shamir secret sharing technology to share the user's private key instead of the master key of the key generation center. Using Gennaro's simulation thought, it is proved that the scheme is robust and unforgeable, so the scheme is safe. Compared with the scheme recently proposed by Cheng et al., the new scheme has higher computational efficiency.