在光子晶体环形腔(PCRR)中把原来移除一圈介质柱改为介质柱半径减小，构成环形线缺陷，提出了一种新型的环形腔结构。运用时域有限差分法，分析了光波在环形腔中的传输特性，并进一步讨论了环形线缺陷介质柱半径变化对滤波特性的影响。结果表明，当环形线缺陷介质柱半径选取在0.43R~0.51R 时，可实现单模窄带滤波，中心波长都处于第三通信窗口1550 nm 附近,归一化透射率均在85%以上，脉宽都在17 nm 以下，为波分复用系统中复用/解复用器的设计提供了有价值的参考。

By decreasing the radius of dielectric rods rather than removing a circle of dielectric rods in the photonic crystal ring resonator(PCRR), an annular line defect is constructed. A new type of photonic crystal ring resonator is proposed. By using the finite difference time domain (FDTD),the transmission property of lightwave through the ring resonator is analyzed. Further more, by changing the radius of dielectric rods, the influences on the filtering property is discussed. The result shows that the narrowband filter with single mode can be realized when the radius of rods is in the range of 0.43R~0.51R. At the same time, the center wavelength is close to 1550 nm at the third communication window, the rates of normalized transmission are all over 85% and the bandwidths are all below 17 nm. It provides available reference for the wavelength division multiplexing (WDM) multiplexer/demultiplexer.