Li5.95Al0.35La3Zr2O12 powder was prepared by sol-gel method with LiNO3, Al(NO3)3·9H2O, La(NO3)3·6H2O, and ZrO(NO3)2·5H2O as raw materials, then polyvinyl alcohol (PVA) aqueous solution was added as liquid medium to prepare Li5.95Al0.35La3Zr2O12 garnet solid electrolyte via cold sintering process. Finally, subsequent heat treatment was employed to improve ionic conduction properties. The density and ionic conductivity of Li5.95Al0.35La3Zr2O12 garnet solid-state electrolyte were evaluated by mass volume method and electrochemical impedance spectroscopy (EIS), the crystal structure and morphology were characterized by XRD and SEM respectively. The results showed that cold sintering holding time and pressure had slight effect on crystal structure of Li5.95Al0.35La3Zr2O12 garnet solid-state electrolyte. The crack was observed for too long cold sintering holding time. The density and ionic conductivity changed slightly for the sample sintered within 15 to 30 min, and impurity phase was detected for short sintering time. It was effective to improve density and ionic conductivity by increasing cold sintering pressure. Li5.95Al0.35La3Zr2O12 garnet solid electrolyte with higher ionic conductivity of 2.66×10-6 S/cm could be obtained at 510 MPa, 200oC and 30 min, which exhibited lower grain boundary resistance. However, the density and ionic conductivity decreased when cold sintering pressure increased further, due to the decomposition of second phase and limitation of grain growth during heat treatment.