Coronary microvascular disease (MVD) refers to exertional angina or myocardial ischemia caused by abnormal structure and/or function of precoronary arterioles and arterioles under the action of various pathogenic factors. The symptoms of patients with coronary microvascular disease are mainly exertion-related chest pain episodes. The basic and clinical researches of the traditional Chinese medicine compound Danshen dropping pills have found that it can improve vascular endothelial function and relieve angina pectoris, and it is widely used in clinical practice. This is a randomized, double-blind, placebo-controlled, multicenter clinical study of Compound Danshen Dropping Pills and blank control in patients with microvascular angina pectoris. The experimental drug and control drug of this clinical trial were selected according to the ratio of 1:1 patients were enrolled in the pre-experiment. After the selected patients signed the informed consent, they were divided into a compound Danshen dripping pill treatment group and a placebo group according to a random, double-blind, placebo-controlled method. Dosage of Compound Danshen Dropping Pills or placebo: 20 capsules each time, 3 times a day, for a total of 6 months. Follow-up was performed every 2 months for a total of 6 months. Primary study endpoints is the difference of the left anterior descending coronary flow reserve (CFR) measured by ultrasound between the two groups compared with the baseline. Secondary study endpoint include the Number of angina attacks per week, the time of angina pectoris and the time of ischemic ST segment depression in exercise test.