Study on the soils of the Zhujiang River Delta showed that the average total K content was 1.68±0.33%, slowly available K 225±139 ppm and exchangeable K 118±52ppm. The potassium content of the soils in the region belongs to the medium level as compared with that of the soils in other reeions of Guandong Province. The slowly available K constituted 1.34% of the total K and the exchangeable K was only equal to 520% of the slowly available K. The content of exchangeable K was decreased from the fringe to the top of the delta.The slowly available K being absorbed earlier in growing stage indicates the less K supply ability of the soils, The curves of the accumulated content of K in various growing stages of rice shows that the content of K in rice plant in the middle growing stage is higher than that by the early and late growing stages. More K absorbed by rice in middle growing stage inticates the better K supply ability of the soil.