Abstract： Objective:To investigate the effects of hyperbaric oxygen（HBO）therapy on the improvement of electrocardiogram（ECG）and symptoms，high-sensitivity C-reactive protein（hs-CRP），and D-dimer（D-D）levels in the patients with unstable angina pectoris（UAP）of coronary heart disease.Methods:A total of 130 patients with UAP of coronary heart disease who were diagnosed and treated in Zhengzhou No.7 People’s Hospital from January 2019 to December 2020 were divided into control group of 63 cases and study group of 67 cases，according to their different treatment methods. The control group was given conventional treatment，and the study group was additionally treated with HBO on the basis of the treatment in the control group. The improvements of ECG and symptoms，serum lipids［total cholesterol（TC），triacylglycerol（TG），high-density lipoprotein cholesterol（HDL-C），low-density lipoprotein cholesterol（LDL-C）］，inflammatory factors［tumor necrosis factor-α（TNF-α），interferon-γ（IFN-γ）］，hs-CRP，and D-D before and after treatment，and the occurrence of major adverse cardiovascular and cerebrovascular events（MACE）during the one year follow-up between the two groups were compared.Results:The total effective rate of ECG improvement in the study group（88.06%）was significantly higher than that in the control group（66.67%）（ P<0.05），and the total effective rate of symptom improvement in the study group（91.04%）was significantly higher than that in the control group（65.08%）（ P<0.05）. After treatment，TC，TG，and LDL-C in the two groups decreased（ P<0.05），and the indexes in the study group was significantly lower than those in the control group（ P<0.05）. After treatment，HDL-C in both groups increased（ P<0.05），and HDL-C in the study group was significantly higher than that in the control group（ P<0.05）. After treatment，TNF-α，hs-CRP，IFN-γ，and D-D were reduced in the two groups（ P<0.05），and those indexes the study group were significantly lower than those in the control group（ P<0.05）. Comparing the incidences between the study group and the control group，the incidence of in-stent restenosis（2.99% vs.12.70%），the incidence of target vessel revascularization（0.00% vs.17.46%），and the total MACE incidence（8.96% vs.46.03%），the incidences of the study group were all significantly lower than those in the control group（ P<0.05）. Conclusion:In the treatment of UAP of coronary heart disease，HBO therapy can effectively improve ECG ST changes，reduce vascular inflammation，D-D and blood lipid levels，and also reduce the occurrence of MACE after surgery. The clinical efficacy is significant.