Abstract: A hydroponic experiment was conducted and regression mathematical models were established for quantitative study of the relation between potassium content of tea seedling plant and potassium concentration in nutrient solution, and the relation between potassium content of shoot and that of tea plant. In addition, the effects of potassium on promoting the synthesis of chlorophyll and photosynthesis were analyzed. The results showed that the potassium content of whole plant, shoot, stem and root, which increased first and then decreased with the increase of potassium concentration in culture medium, reached the maximum in the potassium concentration range of 6.82-8.65 mmol·L^-1, and accorded with the normal distribution curve. The potassium content of mature leaf increased linearly and did not decrease in the test period. The shoot, mature leaf and root, with maximum potassium contents of 20.04, 16.02 and 12.03 mg·g^-1, respectively, contributed greatly to the whole plant potassium content. The maximum potassium content of the whole plant was 10.53 mg·g^-1, and the maximum potassium content of different parts of stem was 8.08-8.27 mg·g^-1. The shoot achieved higher maximum efficiency of content of potassium (1.22) under a lower potassium concentration (3.65 mmol·L^-1) condition than other organs, indicating a stronger ability to accumulate potassium. The shoot potassium content was linear with that of mature leaf and whole plant, while had a first-order exponential relation with that of stem. Potassium accumulation efficiency of root began to fall when potassium concentration was above 5.13 mmol·L^-1, causing the decreased supply of potassium to the shoot. Net photosynthetic rate (P_n) and chlorophyll content variation with the increase of potassium content showed a Boltzman curve, and the optimal potassium content (10.03-10.83 mg·g^-1 in mature leaf and 17.72-19.11 mg·g^-1 in shoot) and potassium concentration in culture medium(4.69-5.96 mmol·L^-1) were found to promote the chlorophyll synthesis and P_n.