Due to the specific mechanical peculiarities, planetary reduction gearmotors were and remain the most progressive types of reduction gearboxes for industry application. Compactness, small specific gravity and, simultaneously, possibility to pass the increased loadings – here what planetary reduction gearmotors are attractive for developers and customers. Because of planetary reduction gearmotors increased amount applying in industry, increases the requirements in their diagnostics. For this purpose the most effective diagnostics is vibration diagnostics. In this article the analysis of vibration diagnostics methods and the analysis of the most effective mounting schemes of vibration sensors (Fig.1) at vibration diagnostics of planetary reduction gearmotor are made.