Abstract: With 311-B optimized saturation design, the regressive maths model was set up based on the relations of plant height and new shoot length and dry weight of tea plants under the condition of water fertilizer coupling. Analysis showed that the interaction effects among these factors were positive on the dry weight of tea plants with the influenced order as N and water>P and water>N and P, and the influence of single factor was N(x1)> water(x3)>P(x2). The optimum combinations of N and P were 0.485g?pot-1 and 0.274g?pot-1, and the irrigation frequency for four to five days every time under the conditions of this experiment.