The invention relates to the technological use of ultrasonic energy and can be used in various industries, in particular in technological processes related to with the production of high-quality medicines and high-purity chemical mixtures, disinfection liquids, filtering, creating high-quality stable emulsions, clarifying wastewater, cold sterilization of milk, activation of liquids and fuel, etc. According to the invention the device for ultrasonic cavitation treatment of liquid contains a tubular structure with
acoustically resolved flanges, made in the form of separate, acoustically resolved and of one or more sealed rings, each of which is on the outer forming surface separate sections of longitudinal resonant ultrasonic vibration drives are placed oscillations with knife-shaped transformers of oscillating speed, and the thickness the ring along the axis is chosen to be less than half the wavelength of longitudinal bending vibrations
in rings, the resonance frequency of ultrasonic vibration drives is equal to the natural frequency radial mode of ring oscillations. At the same time, it is coaxial inside the rings with vibrating ones drives, an additional pipe made of cavitation-resistant and chemically inert material is installed acoustically transparent material for the flow of liquid, which is sealed in the flanges with the formation hermetic closed inter-tube space filled with pre-degassed liquid, the length of the additional pipe is a multiple of half the length of the longitudinal bending wave oscillations in it, it is fixed with sealing in the flanges by nodal points, moreover the frequency of its longitudinal bending vibrations is equal to the natural frequency of the flowing liquid inside the pipe, and the resonance frequency of the radial vibrations of the outer rings, which at the same time placed in the zones of extremes of longitudinal bending vibrations of the additional pipe.