Today, within the framework of the functioning of foreign trade policy, there are two main opposing models: protectionism and free trade. Recently, the situation is developing towards the dominance of the policy of protectionism over the policy of conducting free trade, since there is a continuous increase in the number of non-tariff measures and the manifestation of trade wars. This situation leads to the need for a policy of trade liberalization. Implementing a foreign trade policy aimed at eliminating trade barriers is not a quick process and requires a thoughtful scientific assessment. To analyze the criticality of the situation of the absence of a free trade policy and to reflect its validity, a very wide methodological toolkit is used to study various kinds of trade barriers, ranging from the calculation of the simplest indicators to the construction of complex econometric models. This study provides a comprehensive review of the main methodological approaches to determining the impact of tariff and non-tariff barriers on the international trade activities of countries. In the scientific review work, 4 domestic and 24 foreign sources, formed on the basis of 21 resources, were involved in the search for literature. The results of the review analysis of research papers showed that in the study of tariff and non-tariff barriers, researchers mainly use three econometric models, namely gravity model, partial equilibrium model and general equilibrium model. In addition, the study of non-tariff barriers can be carried out in the context of two other methods besides the econometric one: the implementation of the "price gap" method and the derivation of "incidence indicators".