以短管近似方法导出了分子流在圆截面粘附管内的流动分布及其通过几率和反射几率公式。公式计算结果与蒙特卡罗计算结果进行了对比。以同样的方法导出了各种元件的串联反射几率公式，并作为各种升华泵的抽速计算公式。结果表明，这一套公式可以用于工程计算。本文最后导出了真空元件串联几率的最普遍的计算公式，并对分子泵 的性能测试方法提出了新的建议。 The flow distribution and its probability of passage probability and reflection probability of molecular flow in circular cross-section adhesive tube were deduced by the method of short tube approximation. The formula calculation results are compared with the Monte Carlo calculation results. In the same way, the formulas for the series reflectivity of various components are deduced and used as the formula to calculate pumping speed of various sublimation pumps. The results show that this set of equations can be used for engineering calculations. At the end of this paper, the most common formula for the probability of series connection of vacuum components is deduced, and new suggestions for the performance testing of molecular pumps are put forward.