Requirements of reference source used for spectrum measuring of Fourier transform spectrometer are analyzed.Optical sy stem of Fourier transform spectrometer in developing is presented in this paper. Electrical automatic gain control and phase-locked loop technique has been empl oyed in our system to process frequency stabilized He-Ne laser interferogram si gnal.We have obtained sampling data of light source interferogram by means of th e pulses to extrigger ADC.Electrical simulation and spectral measurement of the output from a He-Ne laser tube at 632.8 nm have been performed by a factor of 8 using a phase-locked circuit.Electronic and optical assisted sampling system c an be used to measure visible,ultraviolet and vacuum ultraviolet spectrum.