As wireless sensor networks (WSNs) are increasingly wi des pread, probability of being under attack also will soar, so the security of WSNs has raised more concern. Broadcast communication plays an important role in WSNs due to the existence of a large number of sensor nodes and the broadcast nature of wireless communications therefore, the security of broadcast communication directly related the safety of the entire network. Authentication is one of the basic security services needed to construct a practical WSNs. In this paper, we present a high-security broadcast authentication protocol. our proposal combines time synchronization with the chinese remainder theorem (CRT) to implement dual authentication. As a result, this scheme has greatly improvement to some existed schemes in term of security