Abstract: In this paper, the situation of all localization DCS transformations is explained by the use of Huaneng Ruiwo HNICS-T316 decentralized control system in a power plant. Combined with the scope and requirements of the DCS transformation, the article explains how to make a reasonable design and layout of the control cabinet and expansion cabinet for the transformation of the original XDPS-400+ system into a fully localized Huaneng Ruiwo system. At the same time, according to the current characteristics of Huaneng Ruiwo system, how to optimize or change the DEH, ETS, MFT system is elaborated. Finally, the author summarizes the successful experience and shortcomings of this DCS transformation. This paper has a good reference effect on other power plant units that are planned to undergo DCS localization transformation.