The relevance. The authors have developed the design and operation principle of a pneumatic compensator for a plunger pump with a submerged magnetoelectric motor, which allows reducing the amplitude of pressure fluctuations at the pump outlet by equalizing liquid flow rate in the lift pipes. It is shown that when using a diaphragm made of reinforced rubber in pneumatic compensators, it becomes resistant to destruction, which in general increases the efficiency and service life of the pneumatic compensator.  The main aim of the research is to develop a pneumatic compensator for a plunger pump with a submerged magnetoelectric motor; conduct a strength analysis and evaluation of the effectiveness of the dіaphragm with reinforcement in pneumatic compensators, which used to reduce the pulsations of the speed and pressure of the fluid flow in the pump and compressor pipes; justify the choice of the diaphragm material of the pneumatic compensator. Objects: downhole pneumatic compensators, submerged rodless plunger pump with linear magnetoelectric motor, column of pump and compressor pipes. Methods: simulation of the diaphragm fixed on a perforated pipe using the software package «Compass 3D» module of the APMFEM; setting the design model of technological parameters in boundary conditions of the design model of technological parameters, at modeling numerical values of speed, flow rate, pressure, temperature similar to the existing well installation. Results. It is established that the maximum stresses that occur in the diaphragm during the operation of the pneumatic compensators are 4 times less than the maximum permissible ones, which shows the operability of the pneumatic compensator in downhole conditions. The positive effect of diaphragm reinforcement in terms of reducing the maximum stresses in the elastic shell is shown. The influence of technological parameters of pneumatic compensators (total gas volume, initial pressure in the gas chamber) on the efficiency of pneumatic compensators is analyzed. The optimal charging pressure of pneumatic compensators is justified, which should not exceed the minimum pressure in the tubing during the pumping cycle, in order to exclude the negative impact of pressing the elastic shell against the perforated pipe (the inner wall of the pneumatic compensator).