Fast frequency hopping (FFH) is a very effective way to combat jamming. In this paper, low density parity check (LDPC) code is employed to enhance the performance of FFH systems over a frequency-nonselective Rician fading channel under band multitone jamming (BMTJ). Moreover, maximum likelihood (ML) diversity combining and various robust diversity combining techniques which need partial or no side information (SI), are considered to improve the system capability of anti-jamming. Simulation results show that the proposed LDPC coded frequency hopping system provides excellent performance against band multitone jamming.