超声波直探头接触法手工检测圆柱形工件曲面时，其声场特征与平面接触工件时有着极大的不同。由于超声波直探头与工件呈线性接触，导致其声场变化，使截面内充满超声场，产生的波型有纵波、横波及沿圆柱表面传播的表面波。根据该声场的特点，结合柱面反射的特殊情况，导致一次底波后产生了不同类型的变型波。通过对三次底波前的变型波的计算和分析，了解了主要变型波的性质和意义，提供了工件内部综合的超声波信息，有助于对圆柱形工件内部质量的评价。

When the ultrasonic beam is used to detect the cylindrical workpiece by manual method, the ultrasonic field characteristics is very different from plane contact workpiece. The ultrasonic field changes because the ultrasonic probe is linearly contacted with the workpiece, leading to a large number of variation waves within its cross section. The waves include the longitudinal wave, transverse wave and wave propagating along the surface of the cylindrical surface wave. In this paper, by calculating and analyzing variation waves before the three bottom wave, the character and significance of the main variation waves can be well understood, thus providing more information for the integrated ultrasonic waves and helping to evaluate the internal quality of cylindrical workpiece.