A method of transmitting a packet, a controller and a cloud management platform are provided. According to an example of the method, the controller may receive a packet from a virtual switch; obtain a forwarding priority corresponding to the packet; and generate a flow entry corresponding to the packet, wherein the flow entry is used to perform encapsulation of a specified type on a packet matching the flow entry and add the forwarding priority into the encapsulated packet; and distribute the flow entry to the virtual switch so that the virtual switch is capable of sending the packet using the flow entry.