Abstract: Nitzschia closterium was cultured by closed-bag device instead of cement pond.By controlling light,temperature and atomsphere can meet the need of its growth.The results show that the effect of closed-bag is better than that of cement pond.Based on the investigation of some impacting parameters,such as relative growth constant,average daily increase amount and average double time,we obtained the optimal conditions for culturing Nitzschia closterium are as follows,illumination time of 5 000~8 000 lx,water te...