A modified algorithm was proposed in this paper to deal with the problem that the conventional algorithm of hard decision decoding for Turbo Product Code(TPC) can not correct some detected error symbols.Based on multiple iteration steps of the conventional algorithm of hard decision decoding,the modified algorithm can correct the wrong symbols by detecting them,estimating their total number,constructing their candidate sequences and then selecting the optimum sequence among the candidates.Simulation results show that the modified algorithm can provide a gain of 0.9 dB over the conventional algorithm at BER of 10-5.