With the growing trend of deploying Software defined networks (SDN) in Internet and data centers, it is necessary to investigate the operation of multicast services in this paradigm shift. We propose an OpenFlowbased virtualized platform to support multiple multicast services simultaneously, each with their own customized multicast algorithms and performance-enhancing strategies for its service requirements. The contributions include: 1) systematic discussions of the technical challenges re-garding to implementing multicast services in SDN, with the proposed architectural components addressing these issues; 2) a virtualized platform enabling user-defined multicast services, independent of current Internet-based protocols; 3) experiments validating the necessity and efficiency of the platform in supporting its design goals and functionalities, with two additional real multicast applications further confirming the feasibility and operability of the proposed prototype.