【Objective】In attempt to provide a theoretical basis for amelioration of acidified red soil through liming and build-up of potassium (K) pool, efforts have been made to explore residual effect of liming on K in rhizosphere and bulk soil in maize field at different maize growth stages in acidified red soil. 【Method】From a long-term fertilization experiment (Started in 1990), designed to have six treatments, including chemical nitrogen and phosphorus (NP), NP plus lime (NPCa), NPK, NPK plus lime (NPKCa), NPK plus straw (NPKS), and NPKS plus lime (NPKSCa) and conducted on a tract of upland maize field of red soil in Qiyang, Hunan Province, samples of rhizosphere and bulk soils were collected in the maize field at the seedling stage, jointing stage, filling stage and harvesting stage of the crop in 2014 for analysis of contents of different forms of K, pH and contents of exchangeable calcium and magnesium (Ca² Mg² ), and exchangeable aluminum (Al³ ).【Result】Results show that 1) compared with Treatment NP, Treatments NPK and NPKS were obviously or 120.4 mg kg^-1 and 149.6 mg kg^-1, respectively, higher in readily available K (RAK) content in both rhizosphere and bulk soils, however, Treatments NP, NPK and NPKS, all suffered K deficiency in rhizosphere at the jointing and filling stages, with deficit being 18.2%, 34.2% and 26.4%, respectively; 2) comparison of Treatments NPKCa and NPKSCa with Treatments NPK and Treatment NPKS, respectively, shows that liming lowered RAK content, respectively, by 46.0 mg kg^-1 and 26.5 mg kg^-1 in rhizosphere soil and respectively, by 68.5 mg kg^-1 and 56.0 mg kg^-1 in bulk soil at the seedling stage, and increased RAK content in rhizosphere by 25.2 mg kg^-1 and 33.7mg kg^-1, respectively, but reduced the content slightly in bulk soil during the period from jointing to harvesting; comparison of Treatments NPCa, NPKCa and NPKSCa with their corresponding non-liming treatments shows that liming increased soil RAK gain and loss rate in rhizosphere soil by 8.6%, 33.2% and 19.3%, respectively, over the whole growing season; 3) soil RAK content in both rhizosphere and bulk soil was significantly and positively related to the corresponding slowly AK (SAK), potassium saturation (KS), K /(Ca² Mg² ) and K /Al³ , and SAK was in ultra-significantly positive relationship and KS in ultra-significantly negative relationship with RAK in relative variation rate. 【Conclusion】Four years after liming in the farmland, under long-term N, P and K fertilization, it is found that liming has increased the contents of RAK and SAK and KS in rhizosphere soil (except at the seedling stage) and the content of (Ca² Mg² ) in rhizosphere soil, but not so significantly as in bulk soil, thus eventually alleviating RAK deficiency in rhizosphere soil.