Abstract:Cymbidium sinense (Andr ) Willd. plants were cultured hydroponically in nutrient solution at different K levels following K starvation in order to compare their growth,development, disease resistance and some Physiological characters. In normal culture condition, the content of K was more than that of N and P, the ratio of N, P, K was 6: 1: 9. Therefore,attention Should be Paid to K fertilizer in cultivated C. sinense. Plant grown at K deficient (0 mmol/L) or low K (0. 1 mmol/L) medium showed inferior growth, fewer flower number and much brown spot disease. If plant grew at normal K supplied conditions (1, 5 or 10 mmol/L), higher rates of Photosynthesis, respiration and stronger activity of root system occurred. Those plants grew rapidly in leaf, existed a considerable number in flower and low rate in leaf brown spot disease. Authors suggest that 5 mmol/L of K is suibole for C. sinense gtowth.