  In the paper [Quantum Inf. Process. 14, 4237-4244 (2015)], Qin and Dai
proposed a proactive quantum secret sharing scheme. We study the security of
the proposed scheme and find that it is not secure. In the distribution phase
of the proposed scheme, two dishonest participants may collaborate to eavesdrop
the secret of the dealer without introducing any error. Incidentally, a
possible improvement of the distribution phase is given.
