The invention relates to the internet technology, and discloses an application program identification method for improving the accuracy of the application identification under the premise of reducing the running load of the network exit equipment. The method comprises the following steps: on the basis of a matching result of file identification information of an executable file and a preset executable file feature library, the internal host determines the application type of the executable file, analyzes the report identification information of a data stream generated by the executable file, and reports the application type and the report identification information to the network exit equipment, the network exit equipment establishes a stream node corresponding to the report identification information of the data stream, and sets priority and flow control policy of the stream node based on the application type of the executable file. Consequently, the judgement of the application of the data stream can be made accurately and rapidly, and the running load of the network exit equipment is reduced greatly. The invention also discloses an internal host and a local network system for the application program identification.