Abstract: Due to the higher requirements for the precision design of turbine blades in small turbo molecular pumps, the difference between traditional single-stage row algorithm and multi-stage rotor-stator combined rows algorithm are compared and analyzed from the perspective of incident direction and position distribution. It shows that there are some principle error in the traditional single-stage row algorithm. Taking the 1st to 4th combined rows as an example, different simulation algorithms are used to compare the transmission probability, the maximum He’s coefficient and the maximum compression ratio. Compared with the multi-stage rows algorithm, the traditional single-stage row algorithm is used to calculate the pumping performance of the turbine rows by about 10% larger. The multi-stage combined algorithm based on rotor-stator rows proposed is the inheritance and development of traditional algorithms, and provides a new theoretical calculation method for the precise design of turbo molecular pumps.