Arthrospira has attracted the attention of scientists and industrialists as a potential human food and dietary supplement around the world being a rich source of numerous nutrients such as proteins, vitamins, amino acids, fatty acids, minerals and antioxidants. The aim of this study was to optimiza the growth spirulina in the laboratory and under outdoor condition in the raceway pond. Growth of A. fusiformis was evaluated in the lab at 8.5, 9, 9.5, 10, 10.5 and 11 pH values using a constant DIC level of 0.23mol. Following this experment the growth of Spirulina evaluation at different DIC (0.02, 0.09, 0.16, 0.23 and 0.3 mol) with the optimum pH value obtained conducted and then the growth performance of both A. fusiformis and A.platensis compared in 60mL test tube. Further the experiment was conducted in outdoor at raceway pond with 3.5m length, 1.9m width and 0.2m depth. The result showed that the optimization of growth rate of A. fusiformis recorded was at a pH level of 10 (1.324±.081 at OD750 and 1.627±0.024 at OD680) and that of the DIC level was 0.23 (1.249±0.040 at OD750 and 1.804 ±0.098 at OD680). Although the highest growth rate was recorded in the pH of 10, the highest drywieght (3.400±0.015) and productivity (0.128±0.001) recored were at the pH of 11 at OD750. With regard to the effect of DIC on the growth of A. fusiformis, the highest drywieght were 0.3 (3.355±0.010) and the highest productivity were high in DIC 0.23 (0.127±0.000) at OD750. The result of mean comparision at six different levels of pH and at five levels of DIC showed significant difference (p<0.05). The result of growth rate comparision both A. fusiformis and A. platensis (commercial spirulina) was not shown significance difference (p<0.05). In the pond experiment, the pond temperature and pH significantly (p<0.05) affected the growth of A. fusiformis strain. The environmental temperature varied between 24.6 and 38.6ºC but it had not significant effect. However, the temperatures of the pond which varied between 27 and 33°C had significant effect (p<0.05). The comparison both of A. fusiformis and A. platensis used in this study, suggests that A. fusiformis can be used in mass production.