Wireless sensor networks are evolving from relatively undemanding applications to applications which have stronger requirements. The coordination of distributed entities and events requires time synchronization. Although a number of methods have been studied for WSNs

but some applications require high precision time synchronization. Precision time synchronization enables a variety of extensions of applications. The IEEE 1588 precision time protocol（PTP） provides a standard method to synchronize devices in a network with sub-microsecond precision. This paper deals with precision time synchronization using IEEE 1588 over wireless sensor networks. Precision time synchronization using IEEE 1588 provides compatibility between heterogeneous systems in WSNs.