A host upgrade method and a device include selecting at least one target host from a plurality of hosts for an upgrade. After the at least one target host is selected, a service running on all virtual machines that are in one or more target service groups and that are deployed on the at least one target host is stopped, and a service running on a virtual machine that is in the one or more target service groups and that is not deployed on the at least one target host is maintained. Then, the at least one target host is upgraded.