A method for scheduling a VM resource, an apparatus, and a system is presented, where the method for scheduling a VM resource includes, when a service device determines that a VM scaling operation needs to be performed on a quantity of VMs used for serving an application, obtaining, by the service device, an application type of the application; determining, by the service device according to a correspondence between a minimum constituent unit of the application and the application type, a quantity of VMs for the VM scaling operation; and performing the VM scaling operation according to the determined quantity of VMs. Therefore, the present disclosure improves appropriateness of a VM scaling operation.