In this paper, we propose multiple sensor nodes identification based on 5 GHz band Wi-Fi system for wireless IoT system. This identification system utilizes backscatter which is used for RFID. Wi-Fi signal and Wi-Fi backscatter signal are multiplied to downconvert to identify sensor node (SN) in the backscatter receiver. Each sensor node (SN) uses different clock frequencies to generate backscatter signals of the received Wi-Fi signal. In the backscatter receiver, the Wi-Fi signal and the backscatter signal are multiplied to downconvert, thus the downconverted spectrum appears in different frequencies for identifying multiple SNs easily. The effectiveness of the proposed system is confirmed by experimental demonstration.