A multi-host system, a host equipment, and an operation method for sharing a human-machine interface device are provided. The host equipment is controlled by human interface device (HID) operation information from another host equipment. The host equipment includes a universal serial bus (USB) host and a USB bridge device. The USB host receives the HID operation information from the another host equipment through a communication channel, and outputs the HID operation information through a USB downstream port of the USB host. A USB upstream port of the USB bridge device is coupled to the USB downstream port of the USB host to receive the HID operation information. The USB bridge device returns the HID operation information in an HID report form to the USB downstream port of the USB host through the USB upstream port of the USB bridge device.