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 22 to July14 and spawning peak period was May and June. Spawning period water temperature range was 24.0℃ to 28.6℃. We finally collected 36,853 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 out3,333 1st instar larvae in 2010. 19 individuals were successfully molted to 9th- instar larvae (after hatching 1070 days). In September 27 2010, among of them 1 individuals were successfully molted to 10th- instar larvae (after hatching 1209 days) and still alive.