Abstract: Based on the rigorous electromagnetic field theory, the rigorous expression of terahertz waves in micro-ring resonators with shape and fishnet structure is given in this paper. With the boundary conditions of electromagnetic field, the enhancement effect of the spatial distribution of terahertz waves in the micro-ring resonator with shape and fishnet structure is analyzed. The numerical results show that the electric field is greater than the magnetic field near the ring resonator metal strips. The electric field near the metal strips is obviously stronger than that in other regions, especially in the opening. The THz electric and magnetic fields in the peak position of electromagnetic field in fishnet structure are symmetry with respect to x. The extremum of the electric field appears in the four up and down corners of the large cross, while the extremum of the magnetic field appears in the upper and lower ends of the small cross. The physical interpretation of these phenomena is also given in the point view of the theory of electromagnetic field transmission lines.