The precise measurement of walking speed in daily life is essential for the health guidance and life prediction of the elderly. Ultra High Frequency (UHF) Radio Frequency Identification (RFID) tags have the advantages of compact size, low cost, no battery requirement, long reading distance, and so forth. In this paper, two reader antennas a certain distance apart are used to measure human walking speed by reading the time difference of the RFID tag. The received signal strength indicator (RSSI) of the RFID tag depends on the distances between the tag and the RFID reader. To calculate the walking speed, the time difference at RSSI maximum points and the discrete generalized cross-correlation algorithm are adopted to estimate the walking speed. The experimental results show that the precise measurement of the walking speed can be realized by employing the maximum time difference method and correlation time difference method. The former combines partitioned Gaussian fitting with Kalman filter, and the latter uses the Phat processor along with SCOT weighting. These methods could be used to measure the daily walking speed of elderly individuals in senior health centres.