A U-shaped waveguide-coupled single micro-ring resonator filter structure is proposed based on two-point coupling and optical interferences controlling phase shift. The mathematical model of this structure is inferred by using the transfer matrix method, and the simulation of the spectral line shape of the output port can be obtained by Matlab. By adjusting the distance of two coupling points between U-shaped waveguide and micro-ring, in contrast to traditional two-straight waveguide-coupled single micro-ring filter, the free spectral range (FSR) of the new structure can be doubled when the distance is integer multiples of the circumference of micro-ring. Aimed at the parameters of this structure, the influence of coupling coefficient on the output line is discussed as well, and the perfect extinction ratio of the output spectrum is gained while a narrow bandwidth and a high quality factor are maintained, as the coupling coefficient is 0.018.