The qualitative composition and quantitative content of the main groups of biologically active compounds of Kazakh plant species of the genus Petrosimonia, collected in the Almaty region, were determined. For the first time a comparative phytochemical analysis of Petrosimonia triandra (Pall.) Simonk. and Petrosimonia brachiata (Pall.) Bunge was presented. Studies of the mineral composition have been carried out. It was revealed that the content of toxic heavy metals (mercury, arsenic, cadmium, lead) in plant raw materials does not exceed the permissible standards. The content of amino acids in plant objects was studied for the first time. A high concentration among amino acids was noted for aspartic (1.246–1.286%) and glutamic acids (2.420–2.502%). This paper presents the results of the analysis of extraction processes with the maximum yield of biologically active compounds from Petrosimonia triandra by two methods: supercritical fluid CO2-extraction and maceration. Gas chromatography-mass spectrometry (GC-MS) was used for the first time in order to detect lipophilic substances in hexane and SCF CO2-extracts from P. triandra. The research results show that these extracts of P. triandra plant are promising sources for obtaining of essential oils, fatty acids and phenolic compounds. Hexane extract from the aerial part of P. triandra exhibits pronounced anti-inflammatory activity.