This paper addresses the issue of diagnosing the transfer function of mass transit hub on the basis of Automated Fare Collection data. A spatial and temporal diagnosis approach is proposed. Our investigation is focused on ‘inter-’ and ‘intra-’ stations diagnoses about passenger flows and facilities. Station transfer function definition, inter-stations diagnosis algorithm and intra-station calculation are depicted. A real case study is applied to the major mass transit transfer hub, the station Bibliotheque Francois-Mitterrand in Paris. Inter-stations study proves that this station is more used during weekdays as a station of commuting travels. Passenger theoretical maximum waiting time is estimated by static transit information. It points out that half of the population waited no longer than a half time headway. The available transit static information helped people to optimize arrival time and waiting time. A Gaussian distributed tap-in passenger flow is observed between two train departure times. Transit intra-station diagnosis assesses the station area efficiency, the gate capacity, gates' rate of use, gate classification and intermodal transfer flows. It points out that the most used area is between the lines RER C and M14. This study enables operators to evaluate its global efficiency of transfer hub including passenger flows and facilities.