As a single carrier modulation scheme，Direct Fourier Transformer Spread Orthogonal Frequency Division Multiplexing(DFT-S-OFDM) has lower Peak to Average Power Ratio(PAPR) than the conventional OFDM. And it has been adopted as the uplink modulation scheme in 3GPP’s Long Term Evolution(LTE). In this work，a new DFT-S-OFDM soft decision algorithm was proposed using the traditional frequency domain linear Minimum Mean Squared Error(MMSE) equalization receiver structure. The statistics of the signal after Maximal Ratio Combine(MRC) and equalization was derived and the output of soft decision was calculated based on the acquired probability distribution. Numerical simulations showed that the proposed method had an approximative 2 dB gain in high code rate scenarios at the cost of little additional computations，and also worked under the non-ideal channel estimation conditions.