Abstract: Based on Chinese remainder theorem, an improved signature scheme is proposed to strictly verify the validity of the parameters transferring between the applicant and group center when a person is applying for joining the group, prevent the information from interpolation and ensure that no impostor can join the group. Then the information on a candidate even impostor is impossible to be included in the signatures, thus providing the irrelevance among all signatures. When deleting a group member, the scheme will restrict the modifications to be made to the public key of the member so as to ensure that no way will the member sign. The proposed scheme solves the problem as shown in Wang's scheme, such as divulging private key, signature relevance, forgery attack of revoked member and invalid join. Analyzed results showed that the proposed scheme can meet the security for the group signature.