Abstract: In Vietnam surface mining, truck is a popular transportation mode, therefore, the problem of selecting a proper fleet is very important to decision makers. Queuing theory is a method with many industrial applications, it offers an interesting approach to the estimation of waiting times because of its calculation speed and relative simplicity. In this research, there is a case study was taken in Cao Son coal mine in Vietnam. Using the queuing model (M/M/1), the result of the model showed the optimized number of truck in the fleet by comparing costs in order to find the minimal value.