Transfer oscillator technology based on femtosecond optical frequency comb is studied, its basic principles are introduced, and the transfer oscillator system is designed and built. The coherent transfer of optical frequency between the master laser and the slave laser is realized. The second-level frequency stability of beat note signal in the system loop reaches the order of 5×10 ^-19. For further evaluation, two sets of transfer oscillator systems are setup to transmit the optical frequency of the master laser to two independent slave lasers at the same time, and the phase noise introduced into the system by the beat note signal of the two slave lasers after locking is analyzed. By improving the signal-to-noise ratio of the beat note signal, optimizing signal processing, and reducing external environmental interference, the two outer beat note signals obtained from the two slave lasers have a line width of less than 30 mHz and the s-level frequency stability of optical frequency transmission reaches the order of 1.4×10 ^-17.