对缺陷渗透理论进行了详细的分析，讨论了渗透材料、缺陷类型、大气压强及缺陷的空间位置等因素对渗透检测灵敏度的影响。采用假设的理想条件：在毛细管内液柱上升过程中，忽略液体的密度，运用流体力学方法导出了动态渗透参量（速率）公式；在裂纹模型渗透过程中，气体的质量和温度均不变，利用热力学定律导出了裂纹模型渗透液渗进量。

The theory of defect penetrant was detailed analyzed, the effects of the penetrant materials, defect types, air pressure and defect position on the inspection sensitivity were discussed. According to the hypothesis: during the rising of liquid pillar, the density of the liquid is disregarded, it infers the parameter of dynamic penetrant by way of fluid dynamic method; It assumes that the temperature and mass of the hermetical gas keep unchanging in the process of the crack model being penetrated, and infers the penetrating volume of the penetrant liquid in the crack model based on laws of thermodynamics.