For the weakness of the frequency-domain narrowband interference suppression methods, the improved adaptive multi-threshold interference detection algorithms and the application of generalized extended approximation algorithm in interference suppression have been put forward. The improved algorithm used the spectrum to remove the interference continues after detection frequency interference detection effect has been significantly improved; there is an element of constraint extension function approximation algorithm, simple structure ,approaching ideas by extension, reducing the time-domain waveform signal processing frequency interference distortion. Matlab simulation verifies the performance of the algorithm throw the contrast of BER, and it is improved the interference detection performance and interference dispose ability of the improved algorithm.