This book constitutes the refereed proceedings of the 41st National Conference on Theoretical Computer Science, NCTCS 2023, held in Guangzhou, China, during July 21-23, 2023. The 16 full papers included in this book were carefully reviewed and selected from 70 submissions. They were organized in topical sections as follows: theoretical computer science, algorithm complexity, artificial intelligence, algorithm design, machine learning theory, computational model, formal methods, network security, software and application security.