Abstract: A field experiment was conducted to study the appropriate rates of N and K and the effects of combined application of Mg and B on Chinese Yam, to provide a basis for high yield and good quality production and rational fertilization. We set three N rates (270, 360 and 450 kg N/hm2) and three K rates (270, 360 and 450 kg K2O/hm2), and studied the effects of equal rate of organic fertilizer (fine organic fertilizer of 4500 kg/hm2) and phosphorus fertilizer (144 kg P2O5/hm2) combined with magnesium (22.5 kg Mg/hm2) and boron (0.21 kg B/hm2) on chlorophyll content, biomass, quality, nutrient uptake and yield. The results showed that the N and K application rates had no significant effect on the foliar SPAD value in tuberous root expansion period and harvest period. Combined application of Mg and B increased soluble protein and amino acid nitrogen significantly. With the increase of N and K, the demand quantity of N and K first increased and then decreased. The tuberous root weight, biomass and yield increased by applying N 360 kg/hm2 with K2O 450 kg/hm2 or N 360 kg/hm2, K2O 360 kg/hm2 with 22.5 kg Mg/hm2. The harvest index of N and K were increased under the application of K with Mg. To achieve the yield of 70000- 90000 kg/hm2, the combined application of K2O/sub> yield.