Egg quality improvement by using Spirulina platensis was conducted in 240 Hy-Line laying hens 18 weeks of ages. The laying hens were randomly assigned to 5 experimental groups (Completely Randomized Design; CRD), 4 replicates of 12 laying hens. Group 1, the chickens were fed control diet without Spirulina platensis (0%). Group 2, 3, 4 and 5 the chickens were fed the control diet in which the 0.05, 0.10, 0.15 and 0.20% Spirulina platensis were added respectively. The egg production performance and egg quality were observed for 24 weeks. The nutritional content in boiled whole egg, amino acid profile in boiled white egg and fatty acid profile, cholesterol content and antioxidant activity in boiler egg yolk were observed at the end of the experimental period. The overall results of the 1-24 weeks showed that of the experimental the Spirulial platensis were not affected on egg production performance, egg quality and boiled egg yolk cholesterol content (P > 0.05) excepted that the using at the level of 0.10 – 0.20% increased egg yolk colour (P < 0.05). The nutritional content in whole boiled egg were not different (P > 0.05) excepted that the using at the level of 0.10 – 0.20% showed the lower crude ash than that of control group (P < 0.05). The antioxidant activity in boiled egg yolk were not found in all experimental groups. The Spirulunina platensis were not affected on fatty acid profile (P > 0.05) excepted that the using at the level of 0.20% decreased margaric acid, elaidic acid, eicosatrienoic acid and docodahexaenoic acid (P < 0.05) but increased arachidonic acid (P < 0.05) and the using at the level of 0.15% decreased elaidic acid and eicosatrienoic acid (P < 0.05). There were no different between amino acid profile in boiled white egg (P > 0.05) excepted that the using at the level of 0.15% increased histidine, hydroxylysine and tryptophan (P < 0.05). Therefore, the Spirulina platensis improved the egg quality and the suitable level for using in laying hen diet is 0.15%. The eggs from the laying hen those fed 0.15% Spirulina platensis can develop to be functional food for the specific need of the consumer.