In order to manage a software project effectively, it is necessary to establish a control method based on the objective and quantitative evaluation data on the current status of the software project. We have already presented quantitative evaluations of the software development process described by Generalized Stochastic Petri-net. However, the evaluations cannot deal with the development period sufficiently because of restrictions on the model. By extending the previous model, this paper proposes a new hierarchical model for software project and a method to evaluate the software process from the viewpoints of the quality, cost and delivery date. The new model, by introducing the concept go ``workload, can take the influence of human factors into account, and thus can evaluate the dynamic aspect of software project. Finally, the result of the case study of the proposed method provide us with some implications on software project management.