The purpose of this study is to accumulate the research data about artificial reproduction of Japanese eel and provide guidance on breaking through the key technology of successful larva survival.On the foundation of the studying on artificial reproduction in Japanese eel for many years,this experiment systematically studied the biological characteristics of embryo and the larva before 19 days incubation used by the methods of observing living body,computer-aided analysis,as well as tissue slice.The results indicated that the time needed 38 h 30 min from fertilized egg to the larva just leaving egg,and the total accumulated temperature was 885.50 ℃?h for this time.The development characteristic of embryo,similar to those of most other teleosts,is a classical meroblastic.The gastrulation is completed by cells wrapped downward and curled inward through yolk.The embryo development of Japanese eel can be divided into 14 stages.However,the development characteristic of larva was different from those of most other teleosts,such as transparent blood cell and Stransformer tubular heart,open oral cavity,3 pairs of genasauria that are developed and cannot close,about 6-9 pairs of neuromast which are located at both sides of body from the 3-day to 9-day of leaving egg,as well as the urohypophysis whose morphology continually changed during the development stages.Analyses for these results indicated that the environment of incubation for the larva of Japanese eel in nature may be very stable,and ingestion feed of larva may depend on the method of bite-after-touch.