This paper aims to investigate multi-source data fusion methods in the context of digital governance to achieve the goal of rural revitalization and development while enhancing the efficiency and quality of data fusion. Firstly, raw data related to rural revitalization and development is collected and pre-processed thoroughly. Next, a weighted multi-granularity fusion operator is developed to establish a solid foundation for multi-source data fusion. Based on this, a data multi-source security fusion scheme is designed, which ensures data security during the fusion process. Test results demonstrate that this method significantly enhances the efficiency of data multi-source fusion, minimizes errors, reduces energy consumption, and produces superior fusion effects.