Petri Nets is a powerful mathematical modeling tool for system description and analysis, with which we can describe the relationship among entities efficiently. The present thesis puts forward the modeling of the distributed computer network - DNMPN and DNMPNTO based on Petri Nets. DNMPN implements the basic function of distributed computer network, and DNMPNTO modifies DNMPN's repetitive forward problem. Thus, it is efficiently helpful to optimize the unit traffic of the network,save the net work resource and improve the efficiency of the network system.