A terahertz frequency comb system is built by using a commercial femtosecond fiber laser and a fiber coupled terahertz photoconductive antenna. The repetition rate frequency of the comb is highly stabilized based on phase-locked technique and the tracking stability is 3.3×10^-13 at sampling time of 100 s. The beat signal between terahertz test source and terahertz frequency comb is achieved with the signal to noise ratio being superior to 50 dB. The absolute frequency of terahertz test source is measured based on the frequency comb method with measuring uncertainty of 5×10^-11.