This book CCIS 2774 constitutes the refereed proceedings of the 40th CCF National Conference of Computer Applications, CCF NCCA 2025, held in Beijing, China, during August 7–9, 2025. The 43 full papers and presented in this book were carefully selected and reviewed from 269 submissions. These papers have been organized in the following topical sections: Artificial Intelligence and Applications Cyberspace Security Technology Data Science and Big Data Technology Frontier Technology Applications