Abstract: Objective To explore the clinical value of implanting a DES （drug eluting stent）in main vessel and dilating a small external diameter balloon in side branch in treating coronary bifurcation lesion. Methods Forty-eight patients who underwent this intervention strategy were retrospectively observed to study its short-term effectiveness and safety. Results The angiographic effectiveness was as follow: Before the operation the degree of main vessel’s stenosis was （86.80%±9.10%）, while the degree of main vessel’s stenosis was （0.20%±0.80%） after the operation （Z=-6.08,P<0.01）. Before the operation the degree of side branch’s stenosis was （67.10%±20.00%）, while the degree of side branch stenosis was （27.30%±18.20%） after the operation （Z=-5.99, P<0.01）. The clinical effectiveness was as follow: No MACEs happened during the operation in this study. The safety was as follow: When the main vessel sent balloon was dilated in （15.10±1.80） atm and the side branch small balloon was dilated in （10.00±2.70） atm, the jailed small balloon and guide-wire in the side branch could be removed smoothly. Conclusion The instant effectiveness and safety of implanting a DES in main vessel and dilating a small balloon in side branch in treating coronary bifurcation lesion is good. But its long-term effectiveness and safety is worth studying further.