Characteristics of waiting lines of oil tankers around the loading berths have been analyzed. This type of waiting line problem can not be solved in general by analytical approach of queueing theory because of its interdependence of characteristics, both for tankers and loading facilities. To this aim a simulation model covering (i) kinds of oil to be loaded for each oil tanker and (ii) loading speeds of each kind of oil at loading berths, are developed. Errors of this simulation model, in terms of average waiting time, for some cases which can be theoretically solved, are estimated. Procedures to utilize this model are also stated.It becomes clear through a check calculation to the actual case that some elements not incluided in the model, such as rules of berth operation, should be taken into, to make the model more powerfull one.