Soil pot experiment at a greenhouse was carried out to investigate the effects of interaction between Mg and K on grain yield,yield components and nutrient uptake of rice (Oryza sativa L.).The results showed that the different application rate of Mg and K fertilizers significantly affected grain yield and its com- ponents of rice.Moreover,the interactive effect of Mg and K was also significant.Moderate application of Mg and K is able to significantly increase grain yield of rice.The highest yield was obtained when the rate of middle Mg and high K was applied.The grain yield increased by 28.4% compared without application of Mg and K fertilizers.When low rate of K was supplied,the uptake of Mg,N and P in straw of rice was in- creased,but their uptake was restrained at high K rate.Under low and medium rate of K supply,the uptake of N,P and K was increased by low rate of Mg supply,whereas the uptake of P and K was depressed at high Mg rate.With an increase of rate of Mg supply,Mg uptake in straw was significantly increased,but it was greatly decreased with increasing application rate of K.The overall results confirmed that there is strong an- tagonistic effect between Mg and K.The balanced application between Mg and K fertilizers has significance on improving grain yield of rice.