The Green Ampt infiltration model is extensively applied in many aspects, and a common means used for simu lation of rainfall infiltration and stream production on slope. Average potential suction S_f and general saturation water conductivity K_s are key parameters of this model. In this paper the mean water content increment Δθ(t) in wetted zone during ponded infil tration was defined. A ponded infiltration experiment was carried out on brown earth in Yantai, indicating Δθ(t) was a constant of 0.34. The relation between general wetting front and actual wetting front was quantified based on the water balance principle, and methods of determining S_f and K_s were put forward on the basis of the relationships of infiltration rate i(t) with cumulation infiltration I(t) or with actual wetting front Z_f^a in graphic characteristics. Compared with the field data, the calculation of infil tration rate and accumulation infiltration based on graphic characterization of i(t)~I(t) and i(t)~Z_f^a was relatively high in accuracy with overall relative error being less than 6%.