Galaxea fascicularis possesses a unique sexual pattern, namely “pseudo-gynodioecy”, among scleractinian corals. Galaxea fascicularis populations on the Great Barrier Reef, Australia are composed of female colonies that produce red eggs and hermaphroditic colonies that produce sperm and white eggs. However, white eggs of hermaphroditic colonies are incapable of being fertilized or undergoing embryogenesis. In this study, the reproductive ecology and fertilization of G. fascicularis were examined in Chinwan Inner Bay, Penghu, Taiwan in Apr.-June 2011 to determine the geographic variation of sexual patterns in G. fascicularis. Synchronous spawning of female and hermaphroditic colonies was observed between 17:30 and 20:00 (1 h after sunset) between 24-28 May 2011 (7-11 nights after the full moon in May), and at same times between 22-24 June 2011 (6-8 nights after the full moon in June). Red eggs were significantly larger than white eggs, although both types of eggs had a distinct nucleus, which was located at the edge of the eggs, suggesting that they were in the final stage of maturation and ready to release gametes. Crossing experiments showed that both white and red eggs could be fertilized in vivo, and they synchronously developed into swimming larvae, suggesting that instead of being pseudo-gynodioecious, the sexual pattern of G. fascicularis is gynodioecious.