The data about algae flora of the mineralized Ulugkol Lake (The State Nature Reserve “Khakassky”). Taxonomic list of seaweed is presented by 109 taxons from specific and intraspecific rank, belonging to 55 genus, 36 families, 9 classes and 5 departments. With respect to species diversity, two division Bacillariophyta – 67 taxons and Cyanoprocaryota – 25 taxons, are distinguished. The greatest number of species has been noted in benthos. Dominants of the plankton and benthos associations are mainly applies to the halophilous and mesogalobous organisms.Key words: algae flora, dominating complex, mineralized lake, Khakasia, South Siberia.