Edge computing gateway is an important device in solutions of distribution Internet of things (IoT). It connects traditional distribution equipments to the IoT cloud platform, and implements the edge comupting matching the cloud service. This paper introduces a function design and system implemention solution of edge computing gateway. In terms of function design, focusing on the public network communication requirements, the northward communication protocol design is introduced, including the data transmission strategy design, communication optioons design, message design based on MQTT; focusing on the edge computing requirements, the paper introduces the device model design and the pipeline style computing model design. In terms of system implementation, the edge computing gateway adopts the component technology and the system consists of a series of independent components, achieving the goal of operation collaboration via message bus. The edge computing gateway product based on the function design and system implementation described in this paper has been tested in certain distribution IoT project, and works as expected.