With the increasing demand for the communication capacity, the optical frequency combs based on micro-ring resonator can satisfy the requirements of communication systems. The optical frequency comb has the features of wide spectrum, high coherence and integration. The optical frequency comb generation is based on the four-wave-mixing(FWM) effect in micro-ring resonator, so the requirement of dispersion curve about resonator is more stringent. This paper summarizes several latest researches about dispersion control of microring resonator, including change the micro-ring width, the combination of slot structure and micro-ring structure, the use of photonic crystal structures. Up on these, we can make a comparative analysis of their strengths, weaknesses and performance. Also there is a prospect on the further optimization of micro-cavity dispersion curves. Utilizing the combination of micro-ring and photonic crystal structure, may realize an optimization of dispersion curves in small spectrum, and improve the efficiency of FWM.