This article puts forward recursive FFT algorithm

which improve the structure of normal FFT algorithm

and change concentrated operation into unequally operation among gaps of sampling points.When sampling frequency is comparatively high and sampling windows are relatively long

it can implement continuous sampling of measured signal and continuous FFT analysis.The method uses hardware PLL（Phase-Locked Loop）to synchronize the sampling window and the measured signal cycle exactly.It is based on high-speed DSP（Digital Signal Processor）TMS320C32-60in order to implement recursive FFT algorithm

then give the results

which shows the possibility to realize the continuous sampling of signals.