From May to October in 1997, the plant, soil and logging water in the wetlands were sampled monthly, and their P and K concentrations were measured. With the method of one-factor non-linear regression analysis, the seasonal dynamics of P and K in two types of wetland i.e., in Carex lasiocarpa-Glyceria spiculosa wetland and in Deyeuxia angustifolia wetland were studied. The concentrations of P and K varied with different species of wetland plant and different organs of the same plant species. But their common property was that the concentration of K was higher than that of P, which shows that the mire-wetland plants had the property of enriching K element. The concentrations of P and K had an obvious seasonal dynamics in plant, soil and logging water, but the patterns were not the same. Some simulation models were obtained, which could be used to forecast the seasonal dynamics of P and K contents.