1. A virtual cluster integration method, wherein the method is applied in a virtual cluster system, and the system comprises M physical machines and N virtual machines hosted on the M physical machines, wherein M and N are integers greater than or equal to 1; and the method comprises: performing a calculation through a search algorithm to obtain the minimum number m of physical machines which are capable of accommodating the N virtual machines, and obtaining G virtual integration solutions for hosting the N virtual machines on the minimum number m of physical machines, wherein m is a positive integer less than or equal to M, and G is an integer greater than or equal to 1; calculating CPU voltage consumption of each virtual integration solution: calculating a CPU utilization ratio of a j th physical machine P ij of an i th virtual integration solution; multiplying the CPU utilization ratio by a maximum value of a dominant frequency of the physical machine P ij to obtain a minimum CPU dominant frequency required by the physical machine P ij hosting a virtual machine; according to the minimum CPU dominant frequency of the physical machine P ij , obtaining a voltage value associated with the minimum CPU dominant frequency from a mapping relationship between a CPU dominant frequency and a voltage, wherein the CPU dominant frequency and the voltage are of a physical machine; and adding up voltage values of m physical machines in the i th virtual integration solution to obtain CPU voltage consumption of the i th virtual integration solution, wherein i is a positive integer less than or equal to G, and j is a positive integer less than or equal to m; and determining a first virtual integration solution according to a minimum value which is of CPU voltage consumption and is calculated and obtained in the G virtual integration solutions; and if there is one first virtual integration solution, determining a virtual integration migration policy according to the first virtual integration solution.