The invention belongs to the technical field of Internet of Things, and specifically relates to an Internet of Things data service middleware system. The system mainly comprises a device management module, a protocol analysis module, a data interaction module, a database access interface, a data push subscription interface and an external system service packaging interface. An external sensor device sends data to the middleware system through a gateway. The device management module determines whether the used protocol is configured in a configuration file in the protocol analysis module according to the data packet. If the protocol is configured, a corresponding virtual entity is established for the sensor, and the data packet is sent to the protocol analysis module. The data packet is unpacked according to the corresponding protocol encapsulation class. The unpacked data enter the data interaction module for unified format conversion and enter a data queue to wait for processing. Three data interfaces are used for providing a database access operation, pushing data to a subscribed user system for a push service system, and transmitting the data to an external service system, wherein the data are as used as the source data of the external service system.