Abstract: To enhance DS/FH TT&C systems anti-jamming capacity, wavelet packet transform (WPT) based narrowband jamming (NBJ) suppression methods (SM) are studied. According to the problem that the NBJ SM based on adaptive WPT is sensitive to jamming frequency, the improved method with double judgement strategy is put forward. By judging simultaneously the energy compaction measures of the father node and the two child nodes, the proposed method reduces misjudgement ratio in the decomposition process, and improves the performance of jamming suppression. In addition, considering that the shift undecimated WPT (SUWPT) SM is not able to counter multiple NBJs, adaptive SUWPT SM is proposed, which adopts tree structure decomposition algorithm so as to track multiple NBJs effectively. Simulation results show that the improved adaptive WPT SM solves the problem of being sensitive to jamming frequency, and adaptive SUWPT SM is able to suppress multiple NBJs.