Aiming at problem that the flooding time synchronization protocol（FTSP） is likely under the attack of sending time

propose a security algorithm which is designed and implemented by adding abnormal drift rate detector and malicious node ID number filter

at the same time

to further improve synchronization precision of FTSP

by weighting to reduce effect of time synchronization of FTSP after malicious attacks and improve formula of time clock drift rate computation in flooding time synchronization protocol. The results of simulation indicate that the security algorithm effectively defends against the hostile attacks of sending time

reduces cost of calculation and the influence caused by malicious attacks

and enhances the robustness. The security algorithm in this paper achieves the goal of improving the synchronization accuracy and stability of flooding time in wireless sensor network.