This work is a further continuation of the investigations presented before at the previous conference «16th International Scientific Conference ENGINEERING FOR RURAL DEVELOPMENT» -Аpplication of Resonance Method for the Examining of the Piston Rings Technical condition. (A. Gasparjans, A. Terebkovs, A. Ziravecka). The basic attention is turned to the improvement of the accuracy of the measurements of the oscillations changings, to the development of the specified mathematical model of the oscillating process. The idea of the method is to cause the oscillations in the ring at the frequency of its own mechanical resonance and at the multiple harmonics. The amplitude of the ring oscillations is measured in the gap by means of sensors according to two coordinates simultaneously. The frequency, phase and amplitude of the oscillations depend on the mechanical properties of the ring’s material and its geometry. Micro-cracks, the areas with stresses, hardening defects, local overheating, loss of elasticity and other defects cause the deviations of frequency, phase and amplitude from the standard. One of the special features of the proposed method is the registration of the frequency response of the piston ring oscillations simultaneously in two planes – radial (the plane of the ring) and in the direction of axis. It allows to discover the defects (microcracks, thermal inhomogeneity, etc.) of the ring independently on their orientation along the assumed axes. This is a kind of non-destructive methods