This book constitutes the refereed post proceedings of the 17th International Conference on Parallel Computational Technologies, PCT 2023, held in Saint Petersburg, Russia, during March 28–30, 2023.The 25 full papers included in this book were carefully reviewed and selected from 71 submissions. They were organized in topical sections as follows: "High Performance Architectures, Tools and Technologies", "Parallel Numerical Algorithms", and "Supercomputer Simulation".