Lateral ventilation system for grain storage has the advantages of conveniently and quickly loading and unloading grains, saving the manpower and material resources. The effect of ventilation uniformity plays an important role in grain storage system. The nitrogen concentration and nitrogen flow uniformity which in the lateral ventilation process of stored bulk grain was analyzed based on the finite volume method of computational fluid dynamics (CFD). The result showed that nitrogen concentration in the whole stored grain was very uniform during lateral ventilation for filling nitrogen, which provided hypoxic environment for storage. It provided a valuable reference for the optimization design of lateral ventilation system.