This article describes the hardware design and software design of ARM-based flow totalizer meter. The greatest advantage of the instrument system can be to measure the measured objects of flow with high accuracy in different regions, having the functions of remote online management over IP. and system software upgrade. At the same time of the flow measurement, pressure and temperature are also measured by the instrument. According to the measured values of pressure and temperature, the instrument can determine the density of the measured object, accumulate the flow without the limit of region and time. So it has some practical value. In order to achieve the functions required by instruments, satisfy software portability and remote online scalability, we use the modular software programming ideas. In order to achieve the accuracy of 0.2%, the error caused by hardware has been amended by software. Through debugging, the flow totalizer meter has achieved the requirement of the instrument design.