Abstract: Femtosecond optical frequency comb is an important research direction in the field of ultrafast laser optics，by locking the repetition rate(f_r)and carrier envelope phase shift rate(f_o)of mode-locked laser to the microwave frequency reference，in the time domain，it presents a series of femtosecond periodic ultra-short sequence pulses，and in the frequency domain，it presents a series of discrete and equally spaced longitudinal mode components，which are widely used in time and frequency transfer，spatial scale measurement，precision spectral measurement and many other metrological scientific research fields.On the basis of introducing the basic principle of femtosecond optical frequency comb，the application research of femtosecond optical frequency comb in metrology field is introduced emphatically，and its important role and significance in metrology field are analyzed.

Key words: Metrology, Femtosecond optical frequency comb, Time and frequency, Space scale, Precision spectral