A trail was conducted to study the beneficial effects of Spirulina platensis algae as a feed additive under different stocking density on broiler performance, physiological status and economic efficiency at 6 week of age. A total of 540 unsexed day- old Ross × Ross broiler chicks were distributed into nine treatments resulted from 3×3 factorial arrangement (60 birds each). Birds were allotted to three groups according to stocking density (10, 12 and 14 birds/m²). Each group was divided into three sub-groups according to adding basal diet along with  Spirulina platensis supplementation levels (0, 0.15 and 0.25 g/kg diet), Body weight, weight gain, feed consumption, feed conversion ratio, mortality rate, carcass trait, some blood metabolites and economic efficiency were studied. The results showed that, all of studied parameters were significantly (P≤0.05) improved at stocking density 10 birds/m² compared to other treatments, the same trend was observed for group fed diet containing spirulina at level of  0.25 g/kg diet. Additionally, an extra improvement in all performance, physiological parameters and economic aspects was showed as a result to interaction between stocking density of 10 birds/m² and supplementation of spirulina at 0.25g/kg diet. Regarding to the effect of spirulina supplementation level and stocking density on broiler performance, physiological status and economical aspect, Spirulina platensis algae could be safely used in broiler feeding, at level of 0.25 g /kg diet and 10 birds/m² stocking density with superior effects on their productive performance. Also, the current study revealed the ability to produce a safety broiler meat for consumers by using natural substances away from antibiotics or other chemicals.