A communication method of virtual machines and a server-end system are provided. A virtual hardware address is assigned to a virtual machine when the virtual machine are established, wherein the virtual hardware address includes a tenant identity. A validation procedure for a packet is performed when the virtual machine desires to communicate with another virtual machine by transmitting the packet, so as to determine whether the virtual hardware addresses of the source-end and the destination-end in the packet have the same tenant identity. If the both virtual hardware addresses have the same tenant identity, the packet is transmitted to the another virtual machine.