A virtual machine allocation method and device are provided in an embodiment of that present invention. The method comprises: according to the degree of preference when each virtual machine is assigned to each physical machine and pheromone, selecting a target physical machine corresponding to each virtual machine from all physical machines, determining the global imbalance after assigning all virtual machines to the corresponding target physical machine, repeating the process of selecting the target physical machine and determining the global imbalance degree until a preset number of times and updating the pheromone according to the minimum value of the global imbalance degree in the preset number of times, repeating the process of selecting the target physical machine and determining theglobal imbalance degree and updating the pheromone until the minimum value of the global imbalance degree determined in the last round is within the preset range; assigning each virtual machine to the target physical machine corresponding to each virtual machine according to the assignment scheme with the minimum global imbalance in the last selection process. The method realizes the load balancing of the physical machine and improves the utilization rate of the physical machine resources.