The horseshoe crab, Tachypleus tridentatus, is known as a living fossil. It plays a very important role in evolution and medical resarch. Horseshoe crab once is attributed widely along the west coast of Taiwan island decades ago. It is almost eliminated from the coast as a result of pollution and degradation. In Taiwan, Tachypleus tridentatus, can only be found in Kimmen and Penghu island. Horseshoe crab in Penghu is facing survival crisis. Thus, conservation need to be done in no time. The objectives of this study are establishment of inducing wild horseshoe crabs natural spawning under the artificial environment. Spawning season began from April 9 to May 13. Spawning period water temperature range was 23℃ to 27.4℃. We finally collected 39,871 horseshoe crab’s eggs altogether in this spawning system to save labor. It’s further to research and develop the circulating water system of fertilized egg hatching- out system. It hatched out 3,599 1st instar larvae in 2012.There were 114 individuals were successfully molted to 10th- instar larvae (after hatching 1,070 days), 57 individuals were successfully molted to 11th- instar larvae (after hatching 1,209 days) and 30 individuals were successfully molted to 12th- instar larvae (after hatching 1,510 days). On July 30 2012, among of them 1 individual were successfully molted to 13th- instar larvae (after hatching 1,881 days) and total 3 individuals still alive.