Relevance. More than 60% of oil wells in Russia are equipped with submersible electric centrifugal pumps. The tendency to increase the share of low- and medium-flow wells changes the operating conditions of submersible electric centrifugal pumps, which may be accompanied by deterioration of heat removal and increased heating of submersible electric motors of pumping units, reduction of the service life of motors. In conditions of decreasing well flow rate, the task of finding the most rational technologies for oil production and efficient operating modes of submersible electric motors is becoming increasingly urgent. Thermal processes of motors are directly related to and largely determined by electromechanical processes of electric motors, although at present there are practically no publications on the joint study of these processes. Aim. To combine the study of thermal and electromechanical processes of submersible electric motors and development the means for their modeling. This can provide a new positive effect in solving the problem of improving the operation of electric centrifugal pumps of low- and medium-flow wells. Object. Combined thermal and electromechanical processes in the system "power source – submersible electric motor – well fluid". Methods: thermal processes modeling in a submersible electric motor based on thermal circuits, taking into account the motor cooling conditions in the well, and electromechanical transient processes modeling, considering the possibilities of regulating the motor power parameters during operation. Results. Comprehensive model of thermal and electromechanical processes of a submersible electric motor, implemented in the Matlab environment and used for numerical simulation of typical operating modes of the submersible electric centrifugal pumps. The results of numerical modeling of submersible electric motor heating in a long-term mode with subsequent transition to a periodic short-term mode during direct starting of the motor confirmed the patterns established by other researchers. It is shown that the design features of the submersible electric motors, which determine its good starting properties, allow using direct start in a short-term periodic mode. However, the impact of temperature fluctuations occurring in the periodic mode is significant. This can lead to an effect on the insulation of the windings and requires further research. The use of a frequency start of the submersible electric motors does not significantly reduce temperature fluctuations. An alternative to short-term periodic operation mode can be the operation of electric centrifugal pumps at reduced speeds of the electric motor, powered by a frequency converter, but this technology has its limitations.