The main propose of this paper is to study the importance of vehicle routing issue and its effect on reducing the cost of unit in companies. These companies, depending on their work, send the raw material and products to depot and, after preparation process, they are distributed to retail outlets. Thus transportation cost is considerable. This has caused companies to reduce cost through reduction of cost of unit. Also in this paper, distribution problem of a major brass manufacturing company in Iran has been studied and an artificial intelligent algorithm (SA) shows that how the cost of unit is reduced by reduction in distribution costs. The results of this research shows that Zobe Aliazh Company has reduced the number of its vehicles from 15 to 12, the distance from 5150 (km) to 41 80(krn) and the time from 110 hours to
99.16 hours. Therefore the results show the distribution cost of this company was reduced from 44417599 Rial to 35863562 Rial.