The antisite defect, electronic conductivity and ionic dynamic properties of LiFePO4 have been investigated using first-principles density functional theory taking into account the on-site Coulomb interaction within the GGA+U scheme. Results indicate the Li/Fe exchange defect is the most preferred to occur in LiFePO4, which causes the Fe—O bond length to change in the direction favoring the formation of Li+ diffusion channels, hence improving the ionic dynamic properties of the olivine LiFePO4.