Objective: To study the effect of nitidine chloride(NC) and hydroxycamptothecine(HCPT) on the development of zebrafish embryo. Method: The 6 h and 48 h post-fertilization zebrafish embryos were randomly treated with NC (5.00

3.15

2.00

1.58

1.12 mg·L-1) and HCPT ( 16.00

10.00

6.50

4.00

2.50 mg·L-1). The death rate and malformation rate of zebrafish embryos were observed after 72 h. Result: 50% lethal concentration (LC50)of was 1.66 mg·L-1 and 50% malformation effect concentration (EC50) was 1.33 mg·L-1 in NC 6 hpf group. LC50 was 2.51 mg·L-1 and EC50 was 2.02 mg·L-1 in NC 48 hpf group. In HCPT 6 hpf group

LC50 was 4.21 mg·L-1

EC50 was 3.29 mg·L-1;LC50 was 7.70 mg·L-1

EC50 was 6.18 mg·L-1 in the HCPT 48 hpf group. Death rate and malformation rate were decreased when the drugs concentration reduced and test time were delayed. Conclusion: zebrafish embryos of 6 hpf are more sensitive to NC and HCPT than embryos of 48 hpf; both NC and HCPT can cause embryotoxicity to zebrafish; NC is more toxic to the development of zebrafish embryos than HCPT.