Narrow-band interference in spread spectrum systems is eliminated by performing a frequency spectrum transform on N sampling points of the data to obtain N points of data; after M transforms, getting an energy accumulation of individual data to obtain N energy values; removing partial excessive large values from the N energy values, averaging the rest, then calculating the threshold value for interference determination based on the average value; identifying all points that have energy values exceeding the threshold value, and performing interference suppression for the data of corresponding points after frequency spectrum transform and finally outputting the data after frequency spectrum inverse transform.