To overcome the problem of interleaving performance deterioration in the pseudo-random row-column cyclic shift interleaver with unbalance between the number of rows and columns of interleaving matrix, a fast interleaver based on pseudo-random mapping is proposed, in which the discreteness and chaotic is improved by scrambling the row number of interleaving matrix before pseudo-random row-column cyclic shifting. The simple implementation, fast calculation and the same excellent performance as the random interleaver of PMFI is shown in theoretical analysis and simulation results. In FH System used Turbo codes under the condition of partial-time noise jamming, PMFI outperforms the common interleaver such as block interleaver, relative prime interleaver et al on bit error rate performance, and improves the anti-jamming gain about 0.6 dB than PRCSI at BER of 10e-5 under the condition of 40% PTNJ. The proposed PMFI could be applied to FH system with unbalance between pulses number and pulse length.