Abstract: The melon variety ‘Yaolong 25’ was used as experimental material, six potassium fertilizer levels were designed by single factor randomized block experiment, the effects of different potassium application rates on K absorption and accumulation quality and yield of melon were studied, in order to provide reference for reasonable application of potassium fertilizer under facility conditions.The results showed that reasonable application of K could promote the absorption and accumulation of K by the whole plant and its organs, the accumulation of dry matter and the growth and development of the plant, improve the nutritional quality of fruit and increase the yield of the melon, while excessive application of K was not conducive to the accumulation of dry matter and the growth and development of the plant.When the potassium application rate was 165 kg·hm^-2,the accumulation of potassium in the whole plant reached the maximum at maturity, which was significantly increased by 428.81% compared with the control.At 135 kg·hm^-2,the average soluble solids content of the whole plant was the best, which increased by 22.68%,21.51% and 33.62%,respectively, compared with the control.Under this potassium application level, the yield of melon reached 4 001.73 kg, significantly increased by 42.94% compared with the control.According to the changes of dry matter in different periods during the growth and development of melon, potassium absorption and accumulation, fruit characters and yield at mature stage, the optimal potassium application rate of 135 kg·hm^-2 was suggested under the same fertility and cultivation environment in this experiment.