介绍了西气东输二线自动超声波探伤对比试样人工缺陷的种类、位置及作用，并分析了对比试样对探伤系统探头数量的要求，两组检测纵向缺陷探头即可完成内外表面纵向刻槽的校验。通过数学方法计算了超声波探头的有效声束宽度，结果表明当钢管壁厚为26.4，27.5和33.0 mm时，即使两组探头可完成对比试样的校验，但探伤系统无法覆盖整个壁厚范围。此时有必要对试样进行完善，建议可在对比试样中增加位于焊缝壁厚中心沿长度方向的 3.2 mm的水平钻孔，以准确对探伤系统在壁厚方向上的检测能力进行检验。

The types, position and functions of artificial defects in automatic ultrasonic testing reference block of the 2nd west-east gas pipeline were introduced, and the requirements of reference block for probe quantity were analyzed. Two group probes could satisfy calibration requirement of surface and internal vertical flaws. Through mathematical treatment method ultrasonic probe effective acoustic beam width was calculated. The results showed that two group probes could not cover the whole weld area when pipe thickness was beyond 25mm. Now it was necessary to perfect the reference block.  3.2mm horizontal drilling should be added into reference block at the weld center along the length direction, in order to check detection capabilities of detecting system in thickness direction accurately.