This study was conducted to evaluate an effect of  different chemicals on survival of Chaetoceros calcitrans as harvesting; furthermore its nutritional contents were evaluated by feeding to Artemia franciscana Vinh Chau interm of survival and growth. The study included of three experiments. The first experiment was performed to harvest algae when applied FeCl3 with three levels of 90mg/L, 120mg/L, 150mg/L, respectively, and four replicates each. Results showed the concentration of FeCl3 150 mg/L promoted the highest harvesting efficiency and survival rate of Chaetoceros calcitrans (i.e. 95.35% and 71%, respectively). The same experiment was carried out by using NaOH to increase pH up to 10, 11 and 12, respectively and four replicates each. The highest rate of algae sedimented was observed at pH=12.. The flocculation efficiency and survival rate of algae were 87% and 83.17%, respectively. The third experiment determined effect of feeding harvested C.  calcitrans algae by FeCl3 150 mg/L (FeCl3 150), NaOH at pH=12 (NaOH 12) and centrifuged algae (centrifuged, the control) to Artemia. Artemia were culture in the density of 100 ind./L. Rearing conditions were 35 ‰ of salinity, aeration, feeding rate 4 times/day. After fourteen days of culture, survival rate and growth of Artemia were not difference significant (p>0.05) among treatments. The highest survival rate was 89.2±6.6% and the length of Artemia was 9.2±0.9 mm at NaOH 12 treatment.