Effects of temperature(15℃, 20℃, 25℃ and 30℃) and Scenedesmus obliquus density(0.75×10⁶ , 1.5×10⁶ , 3.0×10 ⁶ and 6.0×10⁶ cells/ml) on life history parameters including net reproductive rate,intrinsic rate of population increase, genera-tion time,life expectancy at hatching and proportion of mictic offspring, and morphotype in offspring of two Brachionus diversicornis morphotypes were studied by means of individual culture.The results showed that at the four temperatures,the survivorship be-tween the two B.diversicornis morphotypes was similar.The fecundities of the equal-spined rotifers at 15℃, 25℃ and 30℃ were significantly higher than those of the unequal-spined rotifer.Each of the life history parameters between the two B.diversicornis morphotypes was similar,except that the generation time of the equal-spined rotifers was longer than that of the unequal-spined roti-fers at 30℃.The survivorship,the fecundity and each of all the life history parameters between the two B.diversicornis morpho-types were also similar at the four food densities.All the intrinsic rate of population increased,the generation time and the life ex-pectancy at hatching of the two B.diversicornis morphotypes responded differently to increasing temperature,but food density only affected the net reproductive rate and the intrinsic rate of population increase of the equal-spined rotifers significantly.The net re-productive rate of the equal-spined rotifers at algal density of 6.0×10 6 cells/ml was lower than that at both 0.75×10⁶ and 3.0×10 ⁶ cells/ml,and the net reproductive rate at 1.5×10⁶ cells/ml was similar with that at each of all the above-stated three food densities.The intrinsic rate of population increase of the equal-spined rotifers at 6.0×10⁶ cells/ml was lower than that at 3.0×10⁶ cells/ml,but both of them were similar with those at 0.75×10⁶ and 1.5×10⁶ cells/ml.At each of the four temperatures and food densities,the two B.diversicornis morphotypes produced both equal-and unequal-spined offspring.Only at 25℃,the propor-tion of equal-spined offspring produced by the equal-spined mothers was higher than that produced by the unequal-spined mothers.However,at each of all the four food densities,the proportion of equal-spined offspring produced by the two B.diversicornis mor-photypes was similar.Temperature affected the proportion of equal-spined offspring produced by the equal-spined mothers signifi-cantly, but food density did not affect the proportion of equal-spined offspring produced by both the equal-and unequal-spined moth-ers.The proportions of equal-spined offspring produced by the equal-spined mothers at 15℃ and 25℃,and 20℃ and 30℃ were similar,respectively,but the former two were higher than the latter two.