The PR(photoresist) flow process applied to the contact patterning is difficult to predict and optimize because the process model does not exist. In this paper, the PR flow simulation method using the viscous flow model is developed and applied to examine the effect of initial shape and process conditions on the PR flow phenomena. In addition, this model is used to optimize the layout with the various contacts in the real pattern. This PR flow model linking to lithography and etch ones can predict and optimize the contact patterning process in cell, periphery, and TEG(Test Element Group) areas and analyze defects considering the pre-/post-processes systematically.