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.