Cnot2, a subunit of CCR4-NOT, was cloned from the mantle tissue of Pinctada fucata by RACE PCR and named Pf-Cnot2.The complete sequence was 2 616 bp long and the open reading frame was 1 725 bp, which encoded 574 amino acid residues with the theoretical molecular weight of 61 ku and theoretical isoelectric point of 6.25.Protein sequence analysis showed that it was rich in serine, glycine and threonine, and had a conservative NOT2_3_5 domain.Phylogenetic analysis indicated that Pf-Cnot2 had a far evolutionary relationship with Cnot2 of vertebrates.This gene was expressed in tissues of mantle edge, mantle pallial, foot, gonad, visceral mass, adductor muscle and gill in Pinctada fucata, in which, gonad had the highest expression level, followed by gill and mantle pallial.Pf-Cnot2 was expressed during the whole process since trochophore developed into the juvenile shell, and got to its lowest level at trochophore stage.D-shape stage was significantly higher than trochophore stage.The results above provided basic materials for further study of the role that Pf-Cnot2 played in Pinctada fucata.