Using Porphyridium cruentum as the algae strain,the aim of this work was to investigate the effects of different nitrogen concentrations (0,0.5,1 and 1.5 g/L of KNO₃) on the growth and bioactive compounds (phycobiliproteins,extracellular sulfate polysaccharides and polyunsaturated fatty acids) biosynthesis of P. cruentum under the light-emitting diodes (LED) green light.The results showed that P. cruentum could obtain the maximum biomass (3.09 g/L) in the nitrogen concentration of 1 g/L under the LED green light.Moreover,microalga cultivated under LED greed light at 1 g/L and 1.5 g/L KNO₃ achieved the highest concentrations and productivity of phycocyanin,phycoerythrin,allophycocyanin,extracellular sulfate polysaccharide and lipid.Furthermore,P. cruentum attained the highest contents of ARA and EPA at 1.5 g/L KNO₃.However,no significant difference in ARA content was found by microalga between 1 g/L KNO₃ and 1.5 g/L KNO₃.Based on these results,it could draw a conclusion that P. cruentum grown in 1 g/L KNO₃ under LED green light exhibited the excellent growth characteristic and ability to maximally produce phycobiliproteins,extracellular sulfate polysaccharides and polyunsaturated fatty acids.This work addressed the bottleneck about the coproduction of P. cruentum-derived bioactive compounds,offering the scientific reference to cultivate P. cruentum and exploit its bioactive substances for food,feed and cosmetic in future.