To study the stability of geocell reinforced high fill embankment, the settlement and maximum horizontal displacement of plain soil slope and geocell reinforced high fill embankment slope under continuous load were analyzed through laboratory model tests; Based on the indoor model test, a finite element model was established to analyze the settlement amount, maximum horizontal displacement and geocell strain under different reinforcement conditions. The influence of geocell height, laying distance and laying position on the stability of high filled embankment was studied. The result shows that the soil settlement and maximum horizontal displacement of slope can be reduced by laying geocell, and the bearing capacity of slope can be increased. The shear strain of the plain soil slope formed a through slip zone from the top to the foot of the slope. After the geocells were laid, the slip zone penetrated from the surface of the slope into the interior of the slope, and the slip zone was not completely through. With the increase of geocell height, the slope settlement and maximum horizontal displacement first decrease and then become stable, and the safety factor first increases and then gradually flattens. The settlement amount and the maximum horizontal displacement of the slope increase with the increase of the spacing of geocells. The maximum horizontal displacement is reduced by 1.5~2 times, the settlement of slope top is reduced by 1.5~1.8 times, and the safety factor is increased by 1.1~1.3 times. The lateral displacement of high fill embankment mainly occurs at the bottom H/3 of slope. Reducing the spacing of geocell and increasing the height of geocell at the bottom H/3 of slope can better constrain the lateral.