The world seaborne trade has been developing considerably in the last decade, mainly due to globalization and continued development of emerging countries. This world growth has an influence on the development of ports and maritime terminals. It is always a hot topic about how to make the port run in the maximum productivity with minimum cost. But in order to ameliorate the productivity in a confined space ports, it's important to optimize the assignment of the existing distributed resources, such as the cranes, the storages, the vehicles routing etc.. In this paper, given a P-time Petri Net model of a small size or middle size port with repetitive and periodic operation process, we propose a method to adjust the initial setting of system's parameters to keep itself run with maximum productivity and minimum cost. Moreover the necessities for changing the parameters of the resources are studied and a simple mathematical model to evaluate the cost of change is also proposed in the end of the paper.
