With the rapid development of big data technology, new requirements and challenges have emerged for the performance evaluation methods of grassroots employees. This study focuses on the application of big data in performance assessment, providing a detailed analysis of the current methods for evaluating grassroots employee performance and the issues that exist within these methods. It reveals the major challenges that performance evaluation faces in a big data environment. Based on this analysis, the paper proposes an innovative performance evaluation model designed to fully leverage the advantages of big data technology to enhance the fairness and accuracy of assessments. Additionally, it outlines an implementation plan and assessment methods for the new model and presents a feasibility analysis. Ultimately, this research aims to provide a more scientific and reasonable solution for the performance evaluation of grassroots employees, adapting to the developmental needs of the digital age.