Objective To investigate the effect of the compound preparation Guanxinping in improving vascular endothelial function in patients with angina pectoris. Methods A total of 80 patients with angina pectoris were randomly divided into experimental group and control group, with 40 patients in each group. The patients in the experimental group were given Guanxinping in addition to routine drug treatment, and those in the control group were given Xinkeshu in addition to routine drug treatment. The course of treatment was 4 weeks for both groups. The clinical outcome was observed in both groups, and the serum levels of nitric oxide (NO), endothelin-1 (ET-1), thromboxane B2 (TXB2), and 6-ketone prostaglandin F1 alpha (6-keto-PGF1α) were compared before treatment and after 4 weeks of treatment. Results There was a significant difference in the distribution of clinical outcomes between the two groups (P<0.05). After treatment, the experimental group had significant increases in NO and 6-keto-PGF1α and significant reductions in ET-1 and TXB2 (P<0.05); the control group also had significant increases in NO and 6-keto-PGF1α (P<0.05) and reductions in ET-1 and TXB2 (P>0.05). The experimental group had significantly better improvements in these indices compared with the control group (P<0.05). Conclusion Guanxinping can act on vascular endothelial function through various targets, which may be one of its mechanisms of action in the prevention and treatment of coronary heart disease.