Abstract: In CR photographic experiments, it was found that a big gap existed in the measured spatial resolutions for the bilinear image quality meter parallelly placed with the weld seam as compared to the one placed vertical to the seam. It was also found that the vertical placed meter was unable to meet the standard requirements, and only the parallelly placed one could meet requirements by standard. The reason of the phenomenon is due to the different shapes of the X-ray beam focus point, and the finding is verified by experiments. Suggestions on placement direction of dual-wire image quality meter are given.