Today, among the urgent tasks facing the pharmaceutical science of the Republic of Uzbekistan is the study of introduced medicinal plants. Of the promising plants Erva woolly - Aerva lanata Juss of the amaranth family (Amaranthaceae) deserves special attention. A perennial or biennial herbaceous plant grows in many countries of Africa, Saudi Arabia, India, Indonesia, etc. For the first time, Aerva lanata Juss. was introduced on the territory of the former USSR by the Transcaucasian zonal experimental station VILR (Kobuletti) in the mid-70s, then in Ukraine, Uzbekistan and Kazakhstan. Aerva lanata is a dioecious plant. The flowers of A. lanata are nectariferous. Pollination of Erva woolly occurs under the influence of gravity inside the flower, wind, insects and rainwater. Erva woolly with more than one pollination and seed dispersal mode is able to invade a variety of habitats with different environmental conditions and grow as widespread weeds. Among other Aerva species, A. lanata cultivar has a wide range of pharmacological activities such as sedative, antiulcer, antiasthma, antidiarrheal, antioxidant, antihyperglycemic, antimalarial, hypolipidemic and other activities. It is used as a diuretic, for acute kidney damage, as well as for ulcerative wounds, rheumatism. Given the availability of the raw material base necessary to meet the possible growth in consumer demand and its widespread use in traditional and scientific medicine to create effective, low-toxic drugs intended for the prevention and treatment of diseases of the urinary system, Aerva lanata Juss L. was chosen as the object of research. An important stage in the standardization of the final product is the quality control of the technological process and the raw materials entering the production to obtain the finished product. Particular attention is paid to the method of quantitative determination of one of the active substances or groups of biologically active substances that affect the therapeutic effect of finished pharmaceutical products. It is known that the quantitative determination of the active substance is carried out by its extraction from plant materials. In this regard, the problem arises - finding the optimal conditions for the process of extracting the active substance. In view of this, it becomes necessary to conduct research to determine the optimal conditions for the extraction process. The objective of the research: the use of the mathematical planning method of the experiment for the complete extraction of flavonoids from the herb Aerva lanata. To achieve this objective, the following tasks were defined: – selection of the mathematical planning method of the experiment; – selection of method for quantitative determination of flavonoids amount; – statistical analysis of the obtained results. Optimization of the process of extracting the amount of flavonoids from the herb of Aerva lanata, which is predominant in its raw materials, was carried out using the method of mathematical planning of experiments by Box and Wilson. The optimization problem was reduced to determining the values of technological parameters that ensure the maximum yield of total flavonoids from the plant. As an optimization parameter, Y was taken - the content of the sum of flavonoids in the extract, in % of its content in the raw material. Conclusion. This article presents the results of modeling and optimization of the process of obtaining the sum of flavonoids from the herb Aerva lanata Juss. L. A comprehensive quantitative assessment of the influence of three experimental factors (alcohol concentration, hydromodulus and extraction time) on the yield of the total flavonoids was carried out using the method of mathematical planning of the Box-Wilson experiment. The objective was achieved by building a mathematical model based on the first order regression equation: Y=1.20+0.185X1+0.091X2+0.111X3 The adequacy of this process is shown, a mathematical model and parametric identification of this model are presented. As a result of the statistical analysis of the obtained data, the following optimal conditions for the process of extracting the amount of flavonoids from the herb of Aerva lanata were revealed in the quantitative analysis of raw materials: alcohol concentration - 50%; hydromodule - 1:60; extraction time - 30 min. The maximum yield of the sum of flavonoids was 1.52% by weight of dry raw materials. The resulting mathematical model of the extraction process will allow further optimization of the extraction of compounds of natural origin, taking into account the quantitative influence of each factor.