Algal milking has been established as a biotechnological process for the continuous extraction of β-carotene from the Dunaliella bardawil in two-phase systems. The effect of limited nitrogen, high light intensity, and their combination on the production and extraction of β-carotene was followed. The light intensity of 15000 lux was the best stress factor for β-carotene production. A short-term milking experiment for 15 days at 15000 lux and different mixing rates 100, 120, and 150 rpm was performed. The results indicated that the highest total β-carotene production (intracellular and extracellular) was recorded at 150 rpm and 15000 lux with 20% v/v dodecane as a biocompatible solvent. In a preliminary experiment, the light intensity 2000 lux stimulated the cells to recover rapidly and complete the milking for a longer time than the recovery at 15000 lux. In a long-term milking, the experiment consists of ten cycles β-carotene was produced and extracted at 15000 lux and 150 rpm for two days and the cells were recovered at 2000 lux for three days, the process was continued for fifty days. At the end of the experiment, some cells remain alive and were continuously milked for β-carotene. Finally, the total productivity of β-carotene was 58.01 mg/l and the extraction efficiency was about 64%.