To investigate the efficacy and safety of intravascular ultrasound (IVUS)-guided rotational atherectomy (RA) combined with cutting balloon for pretreatment of severe calcified lesions in the coronary artery before stent placement. A total of 120 patients with severe coronary artery calcifications detected by IVUS that required percutaneous coronary intervention (PCI) were recruited from our hospital between January, 2016 to January, 2019. The patients were randomized into two groups for pretreatment of the lesions with semicompliant balloon (SB group, 60 cases) or RA combined with CB (RA+CB group, 60 cases), and drug-eluting stents were implanted after the procedure. The immediate success rate of PCI, vascular parameters detected by IVUS after PCI, and the rates of residual stenosis < 10% were compared between the two groups. The incidences of intraoperative complications and major adverse cardiac events (MACE) within 24 months after the surgery were also observed in the two groups. The immediate success rate was significantly higher in RA+CB group than in SB group (P=0.032). After pretreatment and stent placement, the minimum stent lumen diameter (P=0.035), minimum stent lumen cross-sectional area (P=0.029), immediate lumen acquisition, immediate lumen cross-sectional area acquisition and the rate of residual stenosis < 10% were all significantly higher in RA+CB group than in SB group (P < 0.001). The patients in RA+ CB group showed obviously less residual stenosis of lumen cross-sectional area than those in SB group after the surgery (χ2= 7.859, P=0.005). The incidences of intraoperative complications (χ2=5.997, P=0.014) and MACE within 24 months after the operation (χ2=4.285, P=0.038) were significantly lower in RA+CB group than in SB group. For patients with severe coronary artery calcifications eligible for PCI, RA combined with CB angioplasty can significantly improve the success rate of immediate PCI, expand the lumen diameter and cross-sectional area of the stent after PCI, enhance immediate lumen gain, and reduce the incidence of intraoperative complications and MACE after the operation.