A multicast system is provided. The multicast system includes a multicast processing module and a multicast service module. The multicast processing module is for subscribing to the multicast service module. The multicast service module is for sending a subscribe response to the multicast processing module, and for transmitting data to the multicast processing module via a unicast frame. The multicast processing module is also for identifying a data initiator according to the subscribe response, and for receiving the data from the multicast service module in a multicast mode. A multicast method utilized in the multicast system is also provided.