Microalgae are major primary producers of organic matters in aquatic environments through their photosynthetic activities. Benthic diatom Navicula incerta is the major component of phytoplankton and also relatively easy to cultivate, used as live food source in aquaculture. The growth characteristics of N. incerta were estimated under combinations of temperature, salinity, and light; and also its composition and antioxidant activities were determined. The maximum cell density of 87×105cells/mL, was reached at $20^{circ}C$, $250{mu}mol/m^2{cdot}sec$, 33% salinity, pH 8.3, 12:12 light:dark, and F/2 medium on 2 weeks of the culture period. The antioxidant enzymatic hydrolysates efficiently quenched different free radicals: 1,1-diphenyl-2-pycryl-hydrazyl (DPPH) (pepsin $IC_{50}=196.0{mu}g/mL$), hydroxyl (${alpha}$-chymotrypsin $IC_{50}=102.0{mu}g/mL$), and superoxide (neutrase $IC_{50}=169.0{mu}g/mL$). These results suggest that the enzymatic hydrolysate from N. incerta acts as a candidate against antioxidant and could be used as a potential functional food ingredient.