Abstract： Objective To study the effect of HBO on the levels of plasma nitric oxide (NO), calcitonin gene-related peptide( CGRP), endothelin (ET) and resistin in the patients with heart failure and normal left ventricle ejection fraction. Methods A total of 67 patients with heart failure and normal ejection fraction were randomly divided into the control group ( n = 33) and the HBO group ( n = 34). Levels of plasma NO[(84.61 ±25.64)、(56.41 ± 22.53) mg/L]、CGRP[(51.71 ± 12.98)、(35.98 ± 10.47) mg/L]、ET [(55.94±9.65)、(75. 14 ± 11.23) mg/L]and resistin[(24.60 ±6.78)、(27.40 ±4.68) μg/L]were measured before and after treatment. Results After treatment, the levels of plasma NO, calcitonin gene-related peptide, endothelin and resistin in the patients with heart failure and normal ejection fraction improved obviously for both groups, with more significant improvement for the HBO group. Following treatment, statistical differences in the therapeutic effects could be seen, when comparisons were made between the HBO group and the control group( P ＜ 0. 05 or P ＜ 0. 01 ). Conclusions HBO could obviously improve the metabolic imbalance of NO, CGRP, ET and resistin and enhance the vascular endothelial function in the patients with heart failure and normal left ventricle ejection fraction.