Abstract: Experiments were carried out to study the effects of ecological conditions on the growth and fatty acid composition ofPavlav viridis. The Pavlav viridis was cultured under different temperatures, salinities and illumination intensities. The results showed thatPavlav viridis could grow under experimental temperatures ranging from 5 to 30 e, but the optimum growth temperature was 25 e; The lower salinity was suitable for the algae, and the optimum salinity was 6 j; the suitable illumination intensities ranged from 3000 to 5000lx. The main fatty acid were C14B0, C16B0, C16B1(n-7), C18B1(n-9), C18B3(n-3), C18B4(n-3) and C22B6(n-3), furthermore themaximum DHA content and PUFA(n-3) content of Pavlav viridis were reached at 20e. Lower salinity was good at composing of PUFA( n-3), the top EPA content achieved 6.02% when the salinity was 6 j, while the maximum DHA content reached 17. 79% when the salinity was 15 j. The variation in illumination intensities had an unapparent effect on DHA, but the top EPA has an obvious high content when the illumination intensity was 3000lx. The results also indicated that a relat ively higher DHA and PUFA( n-3) were obtained when the illumination intensities were lower.