In this paper, an improved minimum total path loss (MTP) method combining with power allocation is proposed for the relay node selection. Single-relay assisted single-carrier frequency-division multiple-access (SC-FDMA) for uplink transmissions is characterized. For the sake of exploiting the benefits of the proposed method, we investigate both the direct transmission as well as the traditional MTP and the improved MTP cooperative transmission under the condition of amplify-and-forward (AF) cooperative strategy. Our simulation results show that both the bit-error-rate (BER) and the transmission reliability of the system of the improved MTP algorithm have been improved greatly. In addition, the transmission power is reduced.