To elucidate the modulatory participation of miRNAs in mollusk biomineralization, we have employed high-throughput sequencing to identify miRNAs of pearl oyster, Pinctada fucata. Our study focused on the miRNA expression profile of the mantle, an organ responsible for shell formation of the oyster. The pearl oysters were cultured in the tank with the maintaining conditions of temperature 19 ?, PH 8.1 and salinity 33‰ in recirculating seawater. Overall design: Live and healthy adult pearl oysters P. fucata (shell length 5-6cm and wet weight 30-40g) were obtained from Zhanjiang Pearl Farm (Guangdong, China). Prior to use, the oysters were cultured at controlled temperature 19 ?, PH 8.1 and salinity 33‰ in tanks with aerated artificial seawater for 2 weeks. They were fed with spirulina powder every day. Samples from ten individuals were pooled together to obtain one biological replicate. Total RNA of the mantle tissues was extracted, and fragments of 18-30nt were isolated to generate the small RNA library.