To testify the fate of post-spawning Japanese eel at the last stage of its life history, the post-spawning Japanese eels were simulated to be cultivated in sea water, and the survival rate and reproduction of these eels were observed. The results showed that some post-spawning eels resumed their body energy and started to eat after halt-eating for about 18 days in sea water. All eel resumed eating after about one month. The body weight of male and female eel increased and the survival rate was 94.6% after cultivation for 244 days. Then, the gonads (ovary and testis) of these post-spawning Japanese eel developed and ripened by treatment of exogenous gonadotropin (carp pituitary extract and human chorionic gonadotrophin, CPE and HCG) injection, with silver eel of the year as control. The sections of gonads provided the difference in the process of gonad development and maturation between post-spawning eel and control eel, and revealed that although at first the gonad development of post-spawning was not as good as that of silver eel of the year, after several times injection of hormone, the post-spawning matured with silver eel synchronism which suggested a high sensitivity of germ cells to hormone in post-spawning eel. The oviposition and spermiation in these hormone-ripened post-spawning eel could be induced by 17, 20-dihydroxy-4-pregene-3-one and gonadotropin-releasing hormone analogue (GnRH-A), and larvae could be hatched. The above results effectively proved conclusive evidence that although post-spawning eels were weak they could continue to live and propagate after resumed their body energy.