Abstract: This paper mainly introduces the functions and implementation of the measurement and control system in a gas flow standard device of the 20000l mixed bell jar type as well as the device's working principles. It presents the hardware design of the lower computer and the software development for the upper computer. It also describes the way of realizing three working modes, based on the static volumetric method, the dynamic volumetric method, and the standard meter method, simultaneously in a single device, which greatly enhances the flexibility and mobility of the device. The upper computer of the device adopts VB.NET. The lower computer adopts the integrated module of measurement control cabinet. The configuration and control flow of the measurement control cabinet module and the realization process and functions of the upper computer are described in detail.