Bonded warehouse refers to the warehouse approved and established by the Customs for the storage of imported goods without being managed by the customs tax law and import control regulations. The imported goods stored in the bonded warehouse can be modified, graded, sampled, mixed and reprocessed in the warehouse after approval. If these goods are re exported, they will be exempted from customs duties, and if they enter the domestic market, they will be subject to customs duties. All countries have clear provisions on the storage period of goods in bonded warehouses. The establishment of bonded warehouses can not only facilitate traders, but also promote entrepot trade.