This invention discloses a DNS (Domain Name Server) packet extension method based on DNS message segmentation of an application layer, and relates to the technical field of internet communication. The method comprises the following steps: specifying a DNS message segmentation standard, a representation of a fragment message of the DNS message, an identification and recognition of the DNS message segmentation function of the application layer, and a working principle of the fragment reassembly; by segmenting and reassembling the DNS message on the application layer, breaking through the limit of 512 bytes to the DNS response message; and through using UDP (User Datagram Protocol) transmission, keeping the flexibility of the DNS protocol and simultaneously realizing the expandability of the DNS message. By adopting this method, the problem of reassembly failure of an IP (Internet Protocol) fragment at a receiving terminal due to the fact that the IP fragment is discarded in middleware can be solved; without the need for a TCP (Transmission Control Protocol) connection, the response time can be reduced; the server end is unnecessary to maintain the status information of the TCP connection, and simultaneously compared with the scheme based on TCP, the method has the superiority.