The invention relates to a cloud computing resource allocation method supporting sudden emergency. The method comprises the steps that 1, user resource application information including user priority,urgency degree of resource requirements, resource application quantity and configuration is acquired; 2, the user resource allocation priority is calculated; 3, resource information of a physical server is acquired; 4, the resource utilization rate of the physical server is calculated; 5, a multi-objective function with optimal performance matching of a virtual machine, shortest time provided bythe virtual machine and minimum total load change of a platform and a constraint condition are established; 6, a mapping relation of a virtual machine request and the physical server is established; 7, resource allocation is conducted. According to the cloud computing resource allocation method supporting the sudden emergency, the multi-objective function and the constraint condition are established, a multi-objective optimization algorithm is adopted for obtaining a solution set, a solution is selected as a mapping scheme, and optimal arrangement of the virtual machine can be achieved. Meanwhile, the allocation method has the function of supporting the sudden emergency and can preferentially allocate resources for sudden emergency users.