A hot plug method, a host controller, a host, and a PCIe bridge device. The method includes: generating, by a host controller, a first notification packet, where the first notification packet includes hot plug interruption information, and the hot plug interruption information indicates that a first PCIe device is to be hot-plugged; sending, by the host controller, the first notification packet to a host, so that the host performs, according to the first notification packet, a hot plug operation corresponding to the PCIe device; and receiving, by the host controller, a second notification packet sent by the host, and sending the second notification packet to a user equipment controller, to facilitate the user equipment controller to instruct a user to insert or remove the PCIe device, where the second notification packet is for indicating that the hot plug operation corresponding to the PCIe device is completed.