To reveal the composition, quantity distribution and succession of mollusk species in Nanji Island rocky intertidal zones, quantitative and qualitative surveys were carried out at 7 sections of Nanji Island intertidal zones in November 2013, February, May, and August 2014, and the species composition, quantity and changes in dominant species, species diversity of mollusks were studied. The results include: (1) 63 mollusk species were identified belonging to 3 classes, 113 orders, 34 families and 52 genuses, and the average habitat density and average biomass were respectively 506.5 /m2 and 801.54 g /m2; (2) Septifer virgatus was a common dominant species in all four seasons and of the highest dominance among the species researched; (3) The average Mollusks Shannon-Wiener diversity indexes (H') quarterly were, winter (1.73) > spring (1.69) > Summer (1.58) > autumn  (1.40); (4) In contrast to the historical data, the species number and biomass of Nanji Island mollusk had decreased. The results suggest that mollusk is well-developed in rocky intertidal zones of Nanji Island, with the density and biomass being far higher than that of other neighboring islands, but decreased compared to the data from previous surveys.