Abstract: Physiological functions of potassium, effects of potassium on vegetable yield, quality and resistance to deleterious environmental conditions and interaction of potassium with nitrogen were systematically reviewed. Potassium functioned almost in all metabolic process including photosynthesis, assimilating translocation and distribution, and metabolism of energy, water, nitrogen and so on. In most cases potassium showed positive effects on growth and production of vegetables due to its metabolic roles. Positive effects of potassium on vegetable quality was found, but opposite views were also reported. Suggestions in further research were brought forward on the base of foregoing summarization. More attention should be focused on precise potassium fertilization, insight into physiological functions of potassium and interaction of potassium with nitrogen so that surplus or lack of potassium in vegetable production can be judged easily with either vegetable plant or soil samples.