Abstract: Objective To study the effect of different coronary calcif ication lengths on percutaneous coronary intervention (PCI). Methods Seventy-one patients (71 target lesions) with coronary heart disease (CHD) admitted to our center from July 2012 to January 2013 were divided into calcification group and non-calcification group.Their coronary artery plaques and stenting were assessed and analyzed by intravascular ultrasonography.The characteristics, immediate outcome and major adverse cardiac events (MACE) of PCI between the two groups were observed.The immediate outcomes of PCI were compared when the ratio of calcif ication length> 0.5 or< 0.5 in the lesions with their calcif ication arc ≤180°or> 180°. Results Of the 71 target lesions, 43 were calcif ied and 28 were not calcif ied.The minimal stent diameter was shorter and the minimal stent cross-section area (CSA)was smaller in calcif ication group than in non-calcif ication group (P< 0.05).The pre-expanded stent ratio was lower in calcif ication group than in non-calcif ication group (P< 0.05).The stent expansion index in the lesions with their calcif ication arc ≤180°was signif icantly lower while the stent expansion index in the lesions with their calcif ication arc> 180°was signif icantly higher in calcif ication group than in non-calcif ication group (P< 0.05).No MACE occurred in all patients. Conclusion Coronary artery calcif ication affects the full stent expansion.The stent expansion is obviously restricted in lesions with their calcif ication length ratio> 0.5 when the calcif ication arc is ≤180°and is limited with the calcif ication when the calcif ication arc is> 180°.