Abstract: Endovascular stents are used to dilate vascular stenosis so as to restore blood flow. However, what kind of stenotic blood vessels need stent treatment? It's a biomechanical problem. In this paper, the logical relationship between vascular stenosis, myocardial ischemia and stent treatment was analyzed from the functional evaluation index of vascular stenosis, and the biomechanical mechanism of coronary stent intervention was illustrated with a vivid metaphor of farmland irrigation, so as to inspire readers to think about the basic engineering science principle behind clinical medicine.