The invention discloses a method and a device for realizing the hot plugging of application components. The method comprises the steps: a weak dependency component is mirrored into a memory, when the weak dependency component is updated, the updated weak dependency component is mirrored into the memory once again so as to obtain an updated corresponding mirror component, and when the weak dependency component needs to be invoked, the corresponding mirror component thereof is invoked; a strong dependency component is divided into different component groups according to the mutual dependency relationship thereof, different component groups are loaded to different application domains, when one strong dependency component is updated, the application domain corresponding to the component groupin which the strong dependency component is present is unloaded and the component group in which the updated strong dependency component is present is loaded into the newly-established application domain, and when the strong dependency component needs to be invoked, the strong dependency component is invoked in the application domain corresponding thereto. The technical solution of the method canimplement the hot plugging on the application components and, unlike the prior art, has no need of not only restarting IIS, but also interrupting the operation from a client.