A method for upgrading a Virtualized Network Function, VNF, the method comprising: creating (S110) a virtual machine of a latest version, comprising: before a preset upgrading moment, creating (S210) a first Operation Maintenance Processor, OMP, virtual machine of a latest version; and replacing (S120) a virtual machine corresponding to the virtual machine of the latest version in the VNF with the virtual machine of the latest version; wherein, the VNF comprises a third OMP virtual machine and a fourth OMP virtual machine, wherein the third OMP virtual machine serves as a master OMP virtual machine and the fourth OMP virtual machine serves as a standby OMP virtual machine; wherein replacing the virtual machine corresponding to the virtual machine of the latest version in the VNF with the virtual machine of the latest version comprises: at the preset upgrading moment, replacing the master OMP virtual machine in the VNF with the first OMP virtual machine of the latest version and upgrading the standby OMP virtual machine in the VNF on line, comprising: stopping running (S220) the fourth OMP virtual machine and enabling the first OMP virtual machine, as a standby OMP virtual machine, to access to the VNF; performing (S230) data synchronization between the first OMP virtual machine and the third OMP virtual machine; switching (S240) the first OMP virtual machine to be a master OMP virtual machine, and switching the third OMP virtual machine to be a standby OMP virtual machine; and after online upgrading of the third OMP virtual machine is completed, deleting (S250) the fourth OMP virtual machine. creating (S110) a virtual machine of a latest version, comprising: before a preset upgrading moment, creating (S210) a first Operation Maintenance Processor, OMP, virtual machine of a latest version; and replacing (S120) a virtual machine corresponding to the virtual machine of the latest version in the VNF with the virtual machine of the latest version; wherein, the VNF comprises a third OMP virtual machine and a fourth OMP virtual machine, wherein the third OMP virtual machine serves as a master OMP virtual machine and the fourth OMP virtual machine serves as a standby OMP virtual machine; wherein replacing the virtual machine corresponding to the virtual machine of the latest version in the VNF with the virtual machine of the latest version comprises: at the preset upgrading moment, replacing the master OMP virtual machine in the VNF with the first OMP virtual machine of the latest version and upgrading the standby OMP virtual machine in the VNF on line, comprising: stopping running (S220) the fourth OMP virtual machine and enabling the first OMP virtual machine, as a standby OMP virtual machine, to access to the VNF; performing (S230) data synchronization between the first OMP virtual machine and the third OMP virtual machine; switching (S240) the first OMP virtual machine to be a master OMP virtual machine, and switching the third OMP virtual machine to be a standby OMP virtual machine; and after online upgrading of the third OMP virtual machine is completed, deleting (S250) the fourth OMP virtual machine. stopping running (S220) the fourth OMP virtual machine and enabling the first OMP virtual machine, as a standby OMP virtual machine, to access to the VNF; performing (S230) data synchronization between the first OMP virtual machine and the third OMP virtual machine; switching (S240) the first OMP virtual machine to be a master OMP virtual machine, and switching the third OMP virtual machine to be a standby OMP virtual machine; and after online upgrading of the third OMP virtual machine is completed, deleting (S250) the fourth OMP virtual machine. <EOS>