Sea cucumber species are commercially important in the world. This study explored the reproductive biology of sand fish sea Cucumber in Qeshmisalnd in the Persain Gulf for a year, from December 2012 to November 2013. The macroscopic study intended to examine the features such as gonad color, gonad weight, their length and diameter, and specify the spawning season. Microscopic examinations included histological studies of Hemotoxylin and Eosin (H&E) stained texture slides. We measured early, middle and final stages of gonad diameter by and eyepiece micrometer optimize. Gonad color of male at this stages is white – creamy and gonad color of female stage is orange – red. Based on these criteria, five stages of maturity were determined for both sexes. The result showed that winter is the spawning season in Qeshm area. The correlationn between gonad and different seasons shows meaningful difference (p<0.05).