Features of vibration diagnostics and causes of vibration of vertical booster pump units are considered in the work. On the basis of experimental data and mathematical modeling, the excitation and natural frequencies of vibration characteristic of the pump unit NPV 3600-90-M are determined. It was established that the reverse frequency of the upgraded pump unit in the present case is resonant with its own frequency of the engine-supporting structure system, which is an above-ground part of the equipment under consideration. Taking into account unacceptable limits of ratio of natural and exciting frequencies, optimal range of natural frequency of above-ground part of pump unit is determined.