According to the measurements in Meiliang bay between 1998-2000, the effects of algal bloom on N, P, and K contents were studied. The results showed that the relationship between the Chl a content and temperature was positive. The lowest contents of NH4(+)-N, TN, and TP were obtained in August and September every year, and their total content was positively related to the Chl a content. The annual change of K content was similar to that of N and P. Compared to the 8th sampling point, the content of N and P at 0th and 6th sampling point was higher, and P was not the limiting factor. But in other areas, P was the limiting factor. It also proved that Microcystis spp. grew to form water bloom only when N content was between 1-4 mg.L-1 and TP content was between 0.1-0.3 mg.L-1.