This book constitutes the refereed proceedings of the 18th EAI International Conference on Principles and Practice of Multi-Agent Systems, ChinaCom 2023, held in Sanya, China, in November 2023. The 34 full papers presented were carefully reviewed and selected from 88 submissions. The conference covers a wide range of topics, such as: advanced networking and optimization strategies; signal processing and communication optimization; deep learning applications and optimization; scheduling and transmission optimization; edge computing and artificial intelligence applications;