With the rapid development of Smart Grid, multiple services such as power distribution automation, automatic measurement, user data collection, demand for a reliable, efficient and robust communication network. LTE Private wireless network stands as one promising solution due to its broad bandwidth, low delay, ease deployment and wide coverage, etc. This paper introduces a centralized architecture for the implementation of LTE private wireless network in smart grid communication network. The architecture utilizes the existing optical resources including MSTP/SDH in power grid to facilitate the deployment of private wireless network. Architecture principle and module designs are presented, illustrating an example of applying the centralized architecture into practical implementation.