The article covers one of the pressing theoretical and methodological issues of jurisprudence regarding the role of constitutional law in the system of legal regulation. Using the method of system analysis, the author examines legal regulation, the system of legal regulation, and the legal regulation mechanism. Legal regulation, i.e., the impact on social relations through legal means, is one of the properties of the legal system. The system of legal regulation features simultaneously the integrity, stability and dynamism. The stabilizing role of the system of legal regulation is ensured by the relevant rules of constitutional law, i.e. principles, definitions, and conflict of laws. These rules promote compatibility of the legal regulation system elements, ensure the required completeness of legal regulation, sufficient to regulate important social relations, and legalize the development strategy. The fact that the legal regulation system features the quality of stability does not mean that the system is rigid and not object to change. Dynamism means that the system of legal regulation is in motion, changes its characteristics, loses some elements and acquires others. Such transformations do not affect the stability; they are manifested in a change in the interaction patterns between elements. The rules of the constitutional law, which add dynamism to the system of legal regulation, constitute the rules of behavior; they represent specific regulation. The classification of these rules is based on the main elements of the legal regulation system: a single object of legal regulation; a single method of legal regulation; and the process of regulation. The importance of the role of constitutional and legal rules in the system of legal regulation is highlighted by the analysis of substantive and procedural rules. The rules of the constitutional law contribute to the stability of the legal regulation system, and add dynamism to the system, ensuring the ability of the system to adapt to the performance of various tasks and functions.