The invention discloses a network system of Internet of things and a data processing method thereof, mainly solving the problems of unavailable heterogeneous network integrated access, difficult resource sharing and poor security control of the existing network of Internet of things. The network system mainly comprises an Internet of things processing center, a distributed Internet of things domain processing and servicing subsystem, a multimode Internet of things gateway, and Internet of things devices. The Internet of things processing center provides service and a development platform for the public, the distributed Internet of things domain processing and servicing subsystem assists the Internet of things processing center to provide the service for the user, the multimode Internet of things gateway provides the protocol conversion and the security service, and the Internet of things devices are used to receive and transmit the Internet of things data or to execute instruction, and perform the inter-domain processing or the intra-domain processing on the network data according to different services when processing the network data in the network system of Internet of things. According to the invention, the problem of heterogeneous network integrated access is solved, the resource sharing rate of the Internet of things is enhanced, and the security control of the Internet of things information is strengthened, therefore, the system and the method can be used in designing and building of the Internet of things network.