Passive Optical Network (PON) is the most promising technology in optical access network, and the effective and reasonable upstream dynamic bandwidth allocation (DBA) is the key. This paper proposes a new software defined WDM-TDM PON frame that enable more users to share a single high-capacity fiber access as well as introduce a flexible DBA module to replace the hardware-configured DBA module. The simulation result shows that the delay is reduced up to 23% and the software-defined PON can meet the different priority traffic of QoS in comparison with traditional PON.