This book constitutes the refereed proceedings of the 15th International Symposium on Advanced Parallel Processing Technologies, APPT 2023, held in Nanchang, China, during August 4-6, 2023. The 23 full papers and 1 short papers included in this book were carefully reviewed and selected from 49 submissions. They were organized in topical sections as follows: High Performance Computing and Parallelized Computing, Storage Systems and File Management, Networking and Cloud Computing, Computer Architecture and Hardware Acceleration, Machine Learning and Data Analysis, Distinguished Work from Student Competition.