VSS (verifiable secret sharing) is an important security protection tool in distributed systems. When VSS is employed in publicly verifiable applications, it needs to achieve public verifiability and be upgraded to PVSS (publicly verifiable secret sharing). Besides the two basic security properties, bindingness and hidingness, PVSS concentrates on public verifiability of validity all the operations in VSS so that there is no doubt about any operation and any dispute can be publicly solved. The existing PVSS schemes achieve security and public verifiability at a high cost. Moreover, their public verification operations are not defined and specified comprehensively and in complete details. In addition, most of them are vulnerable to an attack called simple plaintext attack. To overcome those drawbacks in PVSS, a new PVSS protocol is proposed in this paper. It defines public verifiability of VSS in a comprehensive and formal security model, which describes every verification operation in details and can publicly solve any dispute. All the public verification operations are efficiently implemented in the new PVSS protocol, which is more efficient than the existing PVSS schemes. It prevents simple plaintext attack in an efficient way.