Abstract: Multi-level capillary holes are designed to replace a single long capillary hole which is difficult to implement and unsuitable for an adjustable measurement range. Flow field characteristic analysis of multi-level capillary holes is performed. Analytical study results indicate that each capillary hole bears equal pressure drop, there is no obvious pressure drop on large holes between multi-level capillary holes. The relationship between differential pressure and flow rate through multi-level capillary holes is still linear. And the flow rate through multi-level capillary holes equals to that through a single one with the same effective length multiply with a loss factor on the condition that multi-level holes bearing the same differential pressure.