in alginate beads were studied. The main factors during the immobilized culture including CaC1₂ concentrationinitial inoculum density and the density of alginate bead were investigated. The results indicated that With the culture days increasing concentration. The was the highest. The diameter of alginate bead remarkably influenced the growth of benthic diatom in stationary phase and exponential phase. The suitable diameter of alginate beads for cell growth were 2.5-3.0 mm. There was a tendency of increasing at first and then decreasing in growth rate of benthic diatom with the increasing of inoculum density and number of alginate beads. The specific growth rate of benthic diatom in the immobilization groups was about 2 times as much as that in the control groups as the inoculum densities were 2.50×10^{. The optimal density of alginate beads was 220 pills/100 mL. In the experiment of initial inoculum density and the density of alginate beadtotal carbohydrate and crude fat in the control groups were more than that in the immobilization groups. The content result of chlorophyll compared with above result was opposite.}