Traditional green building performance evaluation methods usually rely on static design data and a single evaluation indicator, and lack dynamic monitoring and multi-dimensional data integration, which makes it difficult to connect data at different stages, resulting in a large gap between prediction and actual performance. This paper applies digital construction technology to construct a green building performance prediction and evaluation system that integrates data across stages and dynamically, thereby improving the accuracy and reliability of the evaluation. First, according to Building Information Modeling (BIM) technology, a digital building model containing data such as energy efficiency, environmental impact, and resource utilization is constructed. By deploying Internet of Things (IoT) sensors, energy consumption, temperature, humidity, and air quality in the building are monitored in real-time. The data is transmitted to the cloud platform for centralized processing and visualization, and compared with the design data in the BIM model to provide timely feedback on performance differences. Using big data analysis, support vector machine (SVM), and particle swarm optimization (PSO), data from the full life cycle are analyzed to predict building performance and optimize it. Finally, the LCA (Life Cycle Assessment) method is utilized to comprehensively consider the environmental impacts of buildings such as carbon footprint and resource consumption, and combined with multi-objective decision analysis tools to optimize the green building design and operation plan. The experiment shows that the energy efficiency comparison difference of green buildings is within 10kWh/m², and all indicators are accurately predicted, providing a scientific basis for the design and operation of green buildings.