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".