Method, device and USB (Universal Serial Bus) equipment capable of automatically identifying operating system of host

The invention provides a method, a device and USB (Universal Serial Bus) equipment capable of automatically identifying an operating system of a host. The device is used for external equipment, wherein the external equipment stores respective different system discriminant parameter standard values of various operating systems supported by the external equipment; each operating system corresponds to one message sequence; each message sequence consists of messages which should be sent by the operating system before the external equipment finishes configuration; and the system discriminant parameter standard value corresponding to each operating system is obtained according to the message sequence corresponding to the operating system. The method comprises the following steps: acquisition: obtaining all messages received from a current host by the external equipment before the external equipment finishes the configuration; calculation: according to the received message, calculating a practical value of a system discriminant parameter; and identification: determining the operating system of which the corresponding system discriminant parameter standard value is equal to the practical value as the operating system of the current host. The identification complexity degree of the operating system is simplified, and different operating systems can be subjected to finer-particle distinguishing.