To cope with the ever-increasing requirements on transmission capacity, spectral utilization, energy efficiency, small volume, and system simplicity, wavelength-division multiplexing (WDM) optical fiber communication systems need more advanced laser sources than those conventional laser modules used today. Kerr optical frequency comb generated in integrated on-chip micro-cavity provides a promising candidate as the next generation WDM laser source, thanks to its advantages including broadband spectrum, large number of comb lines, matched frequency interval with WDM channels, highly stable frequency, low phase noise, compatibility for chip integration, and low-cost volume production. The fundamental physics of Kerr optical frequency comb was reviewed and the fabrication methods of various Kerr optical frequency comb devices were introduced. Moreover, the unique merits of Kerr optical frequency comb were discussed, such as high spectral purity and compatibility for chip integration, which could facilitate WDM optical communication in the scenarios of long-haul coherent transmissions and data center interconnects.