This Study Guide is dedicated to the principles of criminal procedure in the process of handling criminal cases, including their concepts, types, legal nature, and essence, as well as issues related to the application of criminal procedure principles and their distinctive features during various stages of criminal proceedings - pre- trial and trial stages. It should be noted that in the investigation, preliminary inquiry, and trial process of criminal cases, the main guiding principles for making lawful, justified, and fair decisions are based on the principles of criminal procedure, and procedural actions are carried out in accordance with them, with relevant decisions being made. This Study Guide is intended for professors, teachers, staff, researchers. students, listeners, cadets, as well as investigators, prosecutors, and judges. This Study Guide was recommended for publication by Resolution No. 256-um of the rector of the Tashkent State University of Law dated November 26, 2025.