通过理论分析和测试对比，确定钢结构熔透对接焊缝中横孔状焊接缺陷当量孔径适用的对比反射体为：RB，CSKIC系列试块上 3 mm长横孔及CSKⅢA试块上的 1 mm短横孔。试验测出RB，CSKIC系列，CSKⅢA试块与测试用试件表面能耗损失为4 dB，将RB，CSKIC系列试块不同深度 3 mm长横孔和CSKⅢA试块上的 1 mm短横孔反射回波幅值分别下调4 dB制作DAC(距离波幅)曲线。经超声波横孔理论回波声压分析，推导出钢结构熔透焊缝中类似于长横孔、短横孔状缺陷当量孔径的计算公式。对于竖孔状缺陷，制作不同孔径、不同厚度钢板的竖通孔反射体，建立波幅孔径曲线及回归函数，中厚板用一、二次波探伤，薄板用三次波探伤，插入法计算当量孔径，并对这种缺陷当量计算方法进行了验证。

The paper, through theoretical analysis and test comparison that the applicable contrastive reflectors in calculating the cross bore weld defect equivalent aperture in steel structure weld penetration were the followings, such as RB,  3 mm long cross bore in CSKⅠC series test block and  1 mm short cross bore in CSKⅢA test block. It was revealed in our experiment that the surface energy consumption of RB, CSKⅠC series test block, CSKⅢA test block and the check bar for test was 4 dB and the DAC curve was made when the dB values of RB,  3 mm long cross bore in the CSKⅠC series test block with various depth as well as the reversed echo of  1 mm short cross bore in CSKⅢA test block were reduced by 4 dB respectively. By echo sound pressure analysis of Ultrasonic Cross Bore Theory, the formula for calculating the defect equivalent aperture of long and short cross bore in steel structure weld penetration was derived. As to the erect bore defect, the dB curve and regression function were made for making erect throughhole reflector with steel plate of various aperture and thickness. The fault detection was made with primary and secondary wave for medium plate and with tertiary wave for thin plate. The method of Sorting by Insertion, the defect equivalent calculating method, was applied in calculating the equivalent aperture and was tested.