Abstract: By means of theoretical analyzing and experimental verifying, two flaws in the public verifiable threshold proactive secret sharing scheme proposed by Shi Runhua, are found.First, the value of threshold k can not be trusted.Second, the attackers can crack the secrets S in terms of public shares update algorithm.At last, new analyzing methods for proactive secret sharing scheme are proposed, which can conduct comprehensive analysis of forward-threshold secret sharing scheme by extending the completeness of proactive secret sharing scheme, and the unidirection of shares updated algorithm.