A CCD camera system monitoring the photon beam position in synchrotron radiation beam line was described. The system provides the photon beam position related to the entrance slit during beam line operation and maintenance. Several beam lines at National Synchrotron Radiation Laboratory have been equipped with it. 10.53 μm and 2.3 μrad resolutions of the position and angle were calibrated respectively.0.37 mm vertical dithers of the photon beam center was detected,coinstantaneously,showing 8083 μradangular deviations. Meanwhile,it offers the reliable basis for beam line testing and diagnosis of the synchrotron facility.