The invention belongs to the field of electromagnetic ultrasonic detection, and relates to an internal inspection electromagnetic ultrasonic thickness measurement energy converter structure of a circular pipeline. The energy converter structure comprises a handle, a coil, a protecting cylinder and a magnet; the connecting steel ring is connected to one end of the handle, and the magnet is a hollowcylindrical magnet formed by combining three equal parts in peripheral direction; the magnet is fixed between the connecting steel ring and the fixing steel ring, the protecting cylinder is sleeved at the outer part of the magnet and bonded with the magnet; the annular coil is arranged in the protecting cylinder, and leads of the coil are coiled and aligned on the same direction with equal space,current directions of adjacent leads are the same. The coil forms a vortex at the inner part closing to the surface of the work piece by alternating current; the magnet generates an offset magnetic field; under the effect of the offset magnetic field, the alternating vortex suffers from the alternating lorentz force; under the effect of the lorentz force, the vortex mass point forms mechanical vibration and generates ultrasound wave, thus pipeline thickness can be judged under different conditions.