In the paper there are considered hollow piezoceramic radially polarized cylinders what are widely used as sound projectors and receivers. The most characteristic run modes of piezoceramic transmitters are resonant modes. An approach to solving of piezoceramic cylinders harmonic oscillations problems on the basis of variational methods is proposed. Two-dimensional harmonic oscillations of polarized by thickness piezoceramic cylinders under electrical loads are studied. Using principle of Hamilton – Ostrogradskii and spline approximations by longitudinal coordinate the system of electroelasticity equations in cylindrical coordinates is reduced to a system of ordinary differential equations by radial coordinate. The suggested approach enables to research the oscillation of transmitters under electrical and mechanical loads at arbitrary boundary conditions. The resulting boundary value problem is integrated by discrete orthogonalization method. The proposed method has a number of advantages over decomposition of solution in series and variational, difference and variationally difference methods, since it involves obtaining a system of ordinary differential equations that is convenient for solving and does not require solving of great order algebraic systems, as in the difference or variationally difference methods, or the summing up of a large number of row members. The developed methodology is used for investigating of harmonic oscillation of cylinders with covered by membrane sides under electric potential loading, founding their resonant frequencies and modes investigation. Obtained results are tested by comparing with results found in the literature and obtained by other methods. The amplitude of movements of the outer surface depending on the loading frequency for the certain body is established. Resonance frequencies correspond to instant changing (great values) of physical characteristics. For investigating of forced vibration electromechanical state of transmitters near the first resonance we built forms of main strain-stress state characteristics at certain frequence. It is established that the maximum radial stresses in the cylinder are much smaller than the amplitude values of longitudinal and circumferential stresses.