In this paper, the authors first review lin et al.'s multi-proxy signature scheme for partial delegation with cheater identification and point out its disadvantages. Then we further propose a modified multi-proxy signature scheme based on Lin et al.'s scheme to eliminate the drawback. The improved multi-proxy signature scheme can provide all security properties mentioned in some literatures. Furthermore, the computational overhead of the modified one is less than Lin et al.'s scheme and some other multi-proxy signature schemes. The improved scheme is simple, efficient and practical.