To analyze the effect of geocell in soil reinforcement, this paper studies high strength geocell. Characteristics of soil reinforced with geocell under different conditions are investigated by indoor triaxial tests using particle flow software. Three dimension particle flow code (PFC$^{3\rm D}$) is used to simulate reinforced stress-strain characteristics of sandy soil under different conditions, the contact force distribution, and distribution regularity of the displacement field. The results show that PFC$^{3\rm D}$ can better simulate characteristics of stress-strain of reinforced sand. With the increase of the welding of geocell, the model of reinforced soil bearing capacity increases. The higher the geocell, the higher the bearing capacity of the reinforced soil. With the increase of confining pressure, bearing capacity of the reinforced sand increases. Displacements of the reinforced sand under load are then analyzed. The results show that the displacement direction of the soil particles in the geocell and its influence area are more concentrated and neater. It is basically along the principal stress direction, spreading outward in the geocell impact area outside the soil particles.