This research article considers the formation, development and activity of the institute of biys in the Kazakh society in the XVIII-XIX centuries. Biys existed during the period of the Kazakh khanate. Representing a special group of socio-political strata of the traditional Kazakh society, performing arbitration function in it, the institution of biys existed for many centuries. Having special powers, they participated in state affairs, organized the management of auls and aimaks. In different periods of the Kazakhstan history, biys played a significant role in the society and the state. If we pay attention to the process of development of traditional Kazakh society, biys represented in it a group of socio-political elite that ruled the country since the founding of the Kazakh khanate between XV-XVIII centuries. A significant change in their status and class position occurred in the XVIII-XIX centuries.  Subsequent political reforms of the Russian Empire in 1822 and 1891 put them in a dependent position on the tsarist administration. Thus, the traditional social structure of the Kazakh people underwent changes and was destroyed. To consider the institute of biys in the Kazakh society as a socio-political structure, the works of domestic and foreign authors were used, as well as archival materials and collections of documents were introduced into the scientific turnover.