Abstract: This paper describes the development of blade-type photon beam position monitor in undulator beamline at HLS (Hefei Light Source) and the photon beam position measurement system. For different gaps of undulator, the calibration of the monitor was carried out. The sensitivity and center positions of photon beam position monitor were measured for different gaps, for example, the horizontal sensitivity and vertical sensitivity are 0.001 5 mm^-1 and 0.852 2 mm^-1 at 40 mm gap. In order to improve the photon beam position monitor, a staggered blade-type photon beam position monitor was introduced. At 40 mm gap, the horizontal sensitivity of the new monitor is 0.551 mm^-1.