Communication system is an important part of the strong Smart Grid, and information access is the key of the strong smart grid communication system. Passive optical network (PON) is the today's most competitive broadband access technology. This paper presents an overview of time-division multiplexing (TDM), wavelength division multiplexing (WDM) and WDM-TDM cascaded PON architectures, and then compares quantitatively their transmission performance under different access bandwidth requirements with the help of Optisystem design software. The comparison and analysis results can provide a theoretical reference to the selection and practical deployment of PON architectures for smart grid applications.