Liquid crystal phase retarder (LCVR) is a new polarization state control device. Correct calibration of its photoelectric characteristics significantly effects the precise optical polarization measurements based on this device. A new testing method including only one polarizer was proposed by modeling light intensity, phase retardation and eigen-axis azimuth. Without rotating any component, multi-wavelength retardations can be rapidly acquired using this simply structured method. In addition, this new setup can be integrated into other polarization measuring instruments for on-line calibration of LCVR. Experimental results show that the repeatability of measured retardations is better than 5‰, while the resolution of eigen-axis azimuth is better than 0.1°.