  Lin et al. [S. Lin, F. Gao, Q.-y. Wen, F.-c. Zhu, Opt. Commun. 281 (2008)
4553] pointed that the multiparty quantum secret sharing protocol [Z.-j. Zhang,
G. Gao, X. Wang, L.-f. Han, S.-h. Shi, Opt. Commun. 269 (2007) 418] is insecure
and proposed an improved three-party quantum secret sharing protocol. In this
paper, we study the security of the improved three-party quantum secret sharing
protocol and find that it is still insecure. Finally, a further improved
three-party quantum secret sharing protocol is proposed.
