In pursuit of high-precision beam position measurements at micrometers or submicrometers for the Shanghai soft X-ray free-electron laser(SXFEL) facility which is under construction in the vicinity of the Shanghai Synchrotron Radiation Facility,a high Q cavity beam position monitor(CBPM) with a resonant frequency of4.7 GHz is developed by the Shanghai Institute of Applied Physics,and the relevant BPM electronics with a dedicated RF front end,and a digital BPM,are completed.The cavity design,cold test,system architecture,and first beam test are performed at the Shanghai deep ultraviolet free-electron laser(Zhao et al.in Nucl Instrum Meth A 528(1-2):591-594,2004.doi:10.1016/j.nima.2004.04.108) facility.Results of the beam experiment show that the performance of the CBPM is consistent with basic expectations,and the beam position resolution can fulfill the requirements for the SXFEL project if the beam conditions are optimized. In pursuit of high-precision beam position measurements at micrometers or submicrometers for the Shanghai soft X-ray free-electron laser (SXFEL) facility which is under construction in the vicinity of the Shanghai Synchrotron Radiation Facility, a high Q cavity beam position monitor ( CBPM) with a resonant frequency of 4.7 GHz is developed by the Shanghai Institute of Applied Physics, and the relevant BPM electronics with a dedicated RF front end, and a digital BPM, are completed. Cavity design, cold test, system architecture, and first beam test are performed at the Shanghai deep ultraviolet free-electron laser (Zhao et al. in Nucl Instrum Meth A 528 (1-2): 591-594, 2004. doi: 10.1016 / j.nima.2004.04.108) facility. Results of the beam experiment show that the performance of the CBPM is consistent with basic expectations, and the beam position resolution can fulfill the requirements for the SXFEL project if the beam conditions are optimized.