Coronary circulation has the important role for myocardial infarction. In recent years, computational simulation has revealed knowledge about heart dynamics. Especially multi-physic and multi-scale heart simulator "UT-Heart" has great contribution on this field. However, UT-Heart cannot calculate peripheral resistance on microcirculation of coronary circulation accurately. In this research, we are performing three dimensional simulation on microcirculation of coronary circulation in order to improve calculation accuracy of UT-Heart. We show the effort and the state of this research in this paper.