The abundance and biomass of ciliate and species richness of tintinnids in the northern South China Sea (21°25. 47′ N-17°24.95′N, 109°28.86′ E-113°13.01′E) were investigated in October, 2007, across 13 sections over 82 stations. Sampling was conducted with Rosette at 0, 5, and 10 m in the area shallower than 15 m; at 0, 10, and the bottom in the case of <30 m in depth; or at 0, 10, 30, and the bottom if the depth >30 m. The results show that 49 species of tintinnids were identified including 16 genera. Genus Tintinnopsis was dominant and seasonal in abundance. The ciliates abundance ranged from 0 to 5757 ind./L in average of (848±776) ind./L, of which aloricate ciliates took (91.9±9)%. The biomass of all ciliates was 0-12.09 μg C/L in average of 1.2-1.54 μg C/L, of which aloricate ciliates took (094±127) μg C/L, or 78.6% to the total. In water column, the abundance of ciliates was 6.4×106-9.1×107 ind./m2 in average of (3.6×106 ±1.4×106) ind./m2; and the biomass was 3.6-195.8 mg C/m2 in average of (48.1±33.7) mg C/m2. Ciliates distributed mainly near coastal shallow waters of warm and less salty with more Chl a. The maximum abundance of ciliate in the study was higher than those in other parts of China seas. However, the maximum abundance of ciliates in the study area corresponded occasionally to a low Chl a concentration.