Abstract: In this paper, a passive channel sounding system specifically designed for the 5G is used to conduct channel measurements on sub-6 GHz frequency bands in time-variant cases on high-speed-train with 250 km/h, and a based-cluster channel model based on measurement data is established. This passive channel sounder, built with dual-channel software-defined radio (SDR) peripherals, high-performance mobile workstation and other ancillaries, can be applied to collection of exact 5G downlink signals with center-frequencies of 2−4 GHz, bandwidth of 100 MHz in in-service 5G new radio (NR) networks. Based on post-processing of downlink signals of different types, multi-dimensional channel power spectra in delay, Doppler frequency and direction of arrival, as well as the estimates of parameters of multipath component (MPC) are obtained. A discussion of the difference between this new 5G-NR model and existing WINNER II model is provided and comments on the model applicability for system performance evaluation.