A threshold decision directed sparse channel estimation (TDDSCE) method was proposed for a Single Carrier Block Transmission(SCBT) system, which can take advantage of the sparsity inherent in high rate wireless communication channels, and improve the channel estimation accuracy. Firstly, a pilot sequence was used to perform a least square (LS) channel estimation, then a decision threshold was derived by obtained channel estimated values. The channel taps whose values were smaller than the decision threshold were forced to be zeros, only the channel taps whose values were above the decision threshold were reserved, so that the sparse channel estimation accuracy was greatly improved. A simulation experiment was carried out based on a COST 207 rural area channel profile, and the results show that the performance of proposed method is most close to that of the known channel case, and its bit error rate (BER) reaches 5×10-4 when the signal to noise ratio is 20 dB. However, the traditional LS channel estimation method only achieves the BER of 3×10-2. The method improves the sparse channel estimation accuracy and reduces the complexity of the SCBT system, and its feasibility is verified by obtained results.