【Objective】To investigate long- and short-term effect of liming on soil potassium (K) in acidifying red soil, a long-term fertilization field experiment on soil fertility and fertilization effect in red soil was initiated in 1990. 【Method】The long-term field experiment was designe to have treatments, i.e. application of chemical nitrogen and phosphorus fertilizer (NP), application of NP fertilizer plus liming (NPL), application of NPK (NPK), application of NPK plus liming (NPKL), application of NPK half of the designed rate and straw returning to make up the remaining half (NPKS), and application of NPKS plus liming (NPKSL), and four levels of liming (0 Lime, 0.5 Lime, 1Lime and 1.5 Lime). Soil samples were collected from the treatments and packed into cylinders separately for indoor soil column leaching experiment. Potassium ion (K⁺) in leachate and readily available potassium (AK), slow available potassium (SAK) and pH in the 0 ~ 50 cm soil layer were monitored throughout the leaching experiment . 【Result】Four years later after the initiation of the experiment, it was found that liming increased the content of SAK in the soil surface (0~10cm) and subsurface layer (0 ~ 40 cm), by 2.06% ~ 36.39% in Treatment NPKSL, and the content of AK in the 0 ~ 10 cm soil layer and the content of SAK in the 10~20cm and 40~50cm soil layers in Treatment NPL by 27.26% and 28.51%, 22.55%, respectively. In terms of K⁺ accumulation in leachate, the limed treatments displayed an order of NPKSL_E > NPKL_E > NPL_E, when liming was kept at the same level. Liming reduced K⁺ accumulation in leachate in Treatments NPKSL_E and NPKL_Eby 18.10% ~ 57.70% and hence K+ leaching rates, too. Liming increased soil pH in the surface soil layer. In the soil with K surplus, liming reduced K⁺ leaching rate by 11.7% for each 1 000 kg·hm^-2 of lime applied. Apparently liming and fertilization are the main factors that significantly affect the mean leaching rate of K⁺ and K⁺ accumulation in leachate. 【Conclusion】 Obviously liming for a short or a long period of time can always increase soil pH in the surface soil layer, and retard vertical migration of AK in the profile, thus increasing the content of SAK in the lower soil layers. The amount of soil leaching K⁺, cumulative K⁺ leaching and K⁺ leaching rate all increase with rising AK content in the soil and with declining liming rate. Liming rationally can effectively reduce the risk of K leaching loss in acidifying red soil.