Digital signature is one of the important problems of cryptography, it is a simulation of traditional handwritten signatures, and can realize sign electronic news. General digital signature scheme includes three processes: system initialization procedures, signature generating process and signature verification process. There are some classic structured multi-signature programs, such as Burmester's, Harn's and Lin's schemes that cannot resist inside attack and outside attack. In this paper, the authors briefly review Burmester's program and relate safety analysis, Burmester's scheme vulnerable to forgery attack. Then they propose a structured multi-signature scheme against forgery attack. In the new scheme, they increase the signature parameter verification to improve security.