In this research, new lithium ion conductor glass-ceramics with NASICON-type structure (Li_1+x+yAl_xCr_yGe_2-x-y (PO₄)₃, x+y=0.5) were synthesized using melt-quenching method and converted to glass-ceramics through heat treatment. Influence of addition of different concentrations of aluminum and chromium in LiGe₂(PO₄)₃ glass-ceramic was investigated for ionic conduction improvement. Substitution of Ge⁴⁺ ions in NASICON structure by Al³⁺ and Cr³⁺ ions induced more Li⁺ ions in A₂ vacant sites to obtain charge balance and also changed the unit cell parameters. These two factors led to ionic conductivity improvement of synthesized glass-ceramics. The glass-ceramics were characterized and the amorth structures were investigated by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), Differential Scanning Calorimetry (DSC) and Complex Impedance Spectroscopy (CIS). The highest lithium ion conductivity of 8.82×10^-3 S/cm was obtained for x=0.4 and y=0.1 (Li_1.5Al_0.4Cr_0.1Ge_1.5(PO₄)₃) crystallized at 850 ^oC for 8 h with minimum activation energy of 0.267 eV.