Familiar methods of camera calibration are very hard to be applied to direct-reading water-meter because the camera on water-meter is limited by operating space and fixing condition. In this study, a new calibration method was proposed by utilizing plenty of round features on water-meter surface. Firstly, the center of round feature was roughly located by template matching. Secondly, the region around round feature was locked. Thirdly, the edge of round feature was extracted by Canny operator and the center of round feature was accurately located according to these edges. Lastly, calibration was carried out with these accurate centers and asymmetric error was corrected. Experimental results showed that the method proposed in this study was practical to calibration for camera fixed on direct-reading water-meter.