This book constitutes the refereed proceedings of the 21st National Joint Conference on Harmonious Human-Machine Environment, HHME 2025, held in Dalian, China, during August 21–25, 2025.The 55 full papers presented in this book were carefully reviewed and selected from 279 submissions.

This book constitutes the refereed proceedings of the 21st National Joint Conference on Harmonious Human-Machine Environment, HHME 2025, held in Dalian, China, during August 21–25, 2025.The 55 full papers presented in this book were carefully reviewed and selected from 279 submissions.