Abstract: To avoid dispute about who are the actual signers, Sun first proposed a nonrepudiable threshold proxy signature scheme with known signers. Hwang et al.(2000) showed that Suns scheme is insecure and made an improvement on Suns scheme. Presently, Tzeng, Tan, Yang found that Hwang, et al.s scheme is vulnerable against the conspiracy. This paper used the method of through intercommunion between original signer group and proxy signer group to achieve secret share and distributed keys, designed a new multi-proxy multi-signature scheme. The new scheme fully meets unforgeability and nonrepudiation requirements.