Abstract: Targeting the velocity measurement and positioning of urban rail transit signaling system, the measurement principle of commonly used wheel speed sensor, Doppler radar and accelerometer is analyzed in detail, and the measurement error factors, failure modes, and complexity of sensors are described in depth. Four typical train velocity measurement and positioning schemes are comparatively analyzed from aspects including measurement precision, costs, system reliability, equipment installation and safety evaluation. The merits and defects of each scheme are described. According to the analysis results, the scheme of combination of wheel speed sensor, accelerometer and transponder has the promising prospect.