The Taoyuan International Airport in Taiwan encountered service capacity bottlenecks for insufficient facilities before COV-19 break. In order to increase the service capacity efficiency on check-in, security checks, and customs clearance, the Ministry of Transportation and Communications R.O.C. (MOTC), Taiwan, rerouted the airport traffic flow by implementing the in-town check-in (ITCI) concept to decrease crowding in the airport waiting hall. This research examined the structure of critical success factors (CSFs) for ITCIs, deriving three hierarchies of three dimensions, eight criteria, and 18 evaluation indexes from the previous literature, expert interviews, and analysis results from Analytic Network Process (ANP) via Super Decisions software. The three CSF dimensions were: first-level hierarchy “advantageous environments,” followed by “marketing” and “service value,” which is a second-level hierarchy. The study concluded that the third level item of “transferred vehicles system and management” can play an important key role in ITCTs and “users’ usage preference” has a high correlation to ITCT management strategy. Those findings are expected to be a valuable reference as operating guidelines for Taoyuan Airport MRT Company and management strategy for airport companies.