This paper provides a summary of the IEEE C37.238-2011 standard. Firstly, it introduces the relationship between the IEEE C37.238 standard and the IEEE1588 standard. Then, it introduces the difference on the parameter and mechanism, which are defined by C37.238 standard and the IEEE1588 standard. And it introduces the characteristic parameters of C37.238. At last, it analyzes the problems and corresponding solutions may be faced by PTP precision time protocol in future applying. It specifies a subset of PTP parameters and options to provide global time availability, device interoperability, and failure management. This set of PTP parameters and options allows IEEE 1588-based time synchronization to be used in mission critical power system protection, control, automation, and data communication applications utilizing Ethernet communications architecture.