An apparatus and a method for online upgrading a kernel-based virtual machine module are disclosed. The method includes reorganizing and compiling a kernel-based virtual machine module to obtain a first running module, the first running module supporting a dual-active mode; and causing a machine virtualizer to use the first running module, obtaining a second running module by compiling according to an upgrade version of codes of the first running module, wherein the second running module is an upgrade version of the first running module, and the machine virtualizer switches to use the second running module.