This book constitutes the refereed proceedings of the 40th National Conference on Theoretical Computer Science, NCTCS 2022, held in Changchun, China, during July 29–31, 2022. The 13 full papers and 6 short papers included in this book were carefully reviewed and selected from 58 submissions.They were organized in topical sections as follows: computational theory and model; approximation algorithms; artificial intelligence; and system and resource scheduling.