In this paper Generalized Side-Lobe Canceller(GSC) is introduced to cancel strong jamming signals from side-lobes of DFT filter banks. For the ith channel, the canceller uses other channels' output to cancel interferefering signals, and places nulls at stop band adaptively, but the length of the canceller' coefficient vector is restricted to 1, so the canceller just cancels strong interferefering signals, with little influence on desired signals in pass band. The algorithms is based on LMS algorithms, but a simplifying method is devised to control the length of coefficient vector, which need no root square and division operations. This method realizes the function of high-order filter banks and especially suited for weak signal detection. Simulations indicate that it reduces computation quantity relative to high-order filter banks but maintains the same performance.