The changes of moisture content in shelled corn samples with different initial moisture content(IMC), low (3.85%～4.21%), normal (9.50%～10.32%) , and high (18.29%～18.65%), were determined in the conditions of 10, 20, 25, 30, 35 ℃ , relative humidity RH 65%, RH 86%, and RH 100%, respectively. A moisture diffusion equation was developed to fit for the relationship between moisture ratio and time. In the range of RH 65% to 100%, the lower IMC, the higher moisture adsorption rate at 10~35 ℃. The moisture adsorption rate or desorption rate increased with an increase in temperature. At RH 65%, RH 86%, or RH 100%, the moisture adsorption rate of corn samples with low IMC below 4.21% at 20~35 ℃ sharply decreased within 120～144 h, but the same samples at 10 ℃ tardily decreased within 192~216 h, then changed gently. For corn samples with normal IMC, its moisture desorption rate at 10~35 ℃ quickly deceased within 72~84 h under RH 65%. At RH 86% and RH 100%, its moisture adsorption rates sharply decreased within 96~120 h and 120~144 h at 10~35 ℃, respectively. The moisture desorption rates of two corn samples with high IMC above 18% at RH 65% and RH 86% sharply decreased within 48~72 h, thereafter changed slowly, but slowly decreased at 10 ℃. The moisture adsorption rates of two corn samples with high IMC above 20% at RH 100% showed similar trend to the moisture desorption rates of the same samples at RH 65% and RH 86%.