Objective To observe the inhibitory effect of Qingre Huoxue Recipe（清热活血方） on angiogenesis of zebrafish embryos and to explore its safety. Methods A total of 120 zebrafish embryos2 days after fertilization were selected and placed in 12-well plates with 10 in each well. They were divided into a blank group

a positive drug group and a Qingre Huoxue Recipe 50μg/ml

100μg/ml

150μg/ml

200μg/ml group. The positive drug group was given Vatarani（PTK787） 3 ml at concentration of 50μg/ml. Each concentration group of Qingre Huoxue Recipe was given 3 ml of the corresponding drug. All groups were continuously administered for 72 h

and the exposure solution was changed every 24 h. The zebrafish embryonic intersegmental vascular index and the number of fluorescence points under the microscope were observed and counted under a stereomicroscope. The maximum non-lethal concentration（MNLD） of Qingre Huoxue Recipe was determined to be 802μg/ml and the minimum total lethal concentration（MTLD） was 2560μg/ml through pre-experiments

and 8 drug concentrations were set in this interval to establish a lethal curve and calculate the half-lethal concentration（LD50）. Three concentrations of 1/10 MNLD（80μg/ml）

1/3 MNLD（267μg/ml）

and MNLD were selected as the drug concentration for observation of toxicity indicators. Drug exposure solution 3 ml was administered for 72 h. The embryo heart rate of zebrafish was counted under microscope

and the effects of Qingre Huoxue Recipe on various organ systems and other phenotypic indicators were recorded

including zebrafish embryo yolk

intestinal cavity

intestinal folds

and tail fins. Results Compared with the blank group

the intersegmental vascular index and microscopic fluorescence points of the zebrafish embryos in the positive drug group and Qingre Huoxue Recipe 100μg/ml

150μg/ml

and 200μg/ml groups were decreased（P<0.01）. Comparing among Qingre Huoxue Recipe 100μg/ml

150μg/ml

and 200μg/ml groups

the intersegmental vascular index of the zebrafish embryonic body decreased significantly with the increase of the concentration of traditional Chinese medicine（P<0.05）. There was only a decreasing trend of fluorescence points under the microscope of zebrafish embryos in each group

and the difference was not statistically significant（P>0.05）. According to the lethal curve of Qingre Huoxue Recipe

the LD50 was 1200μg/ml

and the safety range was 5.1. Compared with the blank concentration

the heart rate of zebrafish embryos significantly increased when Qingre Huoxue Recipe was administered at a concentration of 267μg/ml and 802μg/ml（P<0.01）

and the concentration of 80μg/ml had no significant effects on the heart rate of zebrafish embryos（P>0.05）. There was no significant difference in the rate of increase in heart rate of zebrafish embryos between the concentration of 267μg/ml and 802μg/ml（P>0.05）. When the concentration was higher than 267μg/ml

Qingre Huoxue Recipe showed substantial toxic effects on the development of zebrafish embryos

such as disappearance of intestinal folds and intestinal degeneration. Conclusion Qingre Huoxue Recipe with a concentration of 100μg/ml has a strong antiangiogenic effect on zebrafish embryos and is safe.