Abstract: A. caroliniana is a good green manure, feed and bait plant, which plays an important role in agricultural production. The seasonal variations of yield and contents of N, P of three strains of A. caroliniana were studied by water-soil culture in net room and nutrient solution culture in greenhouse. The results showed that the biomass of three strains was all higher than that of greenhouse culture in spring, summer and autumn, but lower than that of greenhouse culture in winter; and the content of N in greenhouse was higher than that of incubation in net room during spring and summer, but opposite in autumn and winter. And the content of P of 3 strains in greenhouse was higher than that of in net room.