Abstract: The upper computer of the computer monitoring system in a hydropower plant originally used the H9000 system of Beijing Zhongshui Technology Co., Ltd. Due to its long service life, it was transformed into herc8000 system of Guodian Nanjing Automation Co., Ltd. This paper expounds the practical method of gradually transferring the network communication of the lower computer system of the computer monitoring system to the new upper computer system. Realize the smooth transition between the upper computer and the lower computer of the computer monitoring system of the hydropower plant and the dispatching communication, and improve the safe and stable operation of the hydropower plant. This practice provides a good reference for the implementation of the same type of reconstruction project.