A series of La_0.67Ca_0.33-0.5xLi_xMnO₃ ceramic (x=0.00, 0.05, 0.10, 0.15, 0.20) were prepared by sol-gel technique. The crystal structures were analyzed by X-ray diffraction (XRD), the surface morphology and grain boundaries were investigated by scanning electron microscope (SEM), and the temperature dependence of the resistivity (R-T) of the bulk samples were studied by the standard four-probe method. It can be indexed with an orthorhombic structure for all of La_0.67Ca_0.33-0.5xLi_xMnO₃ polycrystalline ceramics. The results showed that with the increase of the content of Li element, the unit cell volume decrease and the resistance increases. The insulator-metal transition temperature T_P shifts to lower temperature and the temperature coefficient of resistivity (TCR) decrease continually. The data of resistivity on low-temperature (T_P) have been fitted with the relation ρ(T)=ρ₀+ρ₂T ²+ρ_4.5T ^{4 . 5}, the high-temperature (T>T_P) resistivity data were explained using small-polaron hopping (SPH) and variable-range hopping (VRH) models. The resistivity data in whole temperature range (100—300 K) can be fitted by percolation model. Polaron activation energy E_a is found to increases with increasing the contant of Li (x), which suggests that Li doping decrease bond angle of Mn ³⁺-O ^2--Mn ⁴⁺, thereby the increase of effective band gap and the decrease of double exchange coupling, this is the reason of the increase of resistivity.