This study aims to investigate the temporal-spatial distribution and reproduction of the Callionymidae, a dominant bottom-dwelling family at southwestern Taiwan. Samples were collected once every 1~2 month from January 2001 to January 2005 at seven stations, including Jiading, Zuoying, Jhongjhou, Linyuan, Dapeng Bay, Linbian and Fangliao, along the southwestern coast of Taiwan. A total of 5,846 samples was obtained, including 3 genera and 15 species. More species were found in this study than previous ones. The distribution of callionymids showed the significant variations in season, site and year. The highest abundance months occurred during March to October annually, with the most abundant at Jiading, then decreased in numbers southwards. Callionymus planus (52%)¡BCallionymus curvicornis (28%)¡BCallionymus virgis (7%) and Callionymus filamentosus (6%) were the top four dominant species. The four dominant species appeared abundantly around their spawning season. C. planus, C. curvicornis and C. filamentous were serial spawners, with peaking period at March-May, November-March and February-April, respectively. Both C. planus and C. curvicornis were most abundant at Jiading, and decreased southwardly, whereas the C. virgis and C. filamentosus were most abundant at Fangliao and Zuoying, respectively. All dominant species were revealed resource partitioning in relation to their reproductive activities. Callionymus planus that grew fast and recovered quickly among the callionymids, predominated in this area. Both C. planus and C. curvicornis showed significant reproductive isolation at the same area, both with a southward decrease in number. Calllionymus virgis separated from others and lived in the southmost site. Furthermore, C. filamentosus had a spawning period between C. planus and C. curvicornis.