In the postal delivery service, both the standardization of business process and the workload measurement is very important part of saving the cost and improving the efficiency. However, these are not easy to apply to real situation because of the labor-intensive and diversification of delivery environment. In this study, we develop the methodology for the standardization of business process and workload measurement model of the postal delivery service. Firstly, we introduce the work factor analysis on the postal delivery process. Then, we propose the methodology workload measurement model based on diversification of delivery environment.