The Chenghua emperor period of the Ming dynasty was an important node of social transformation. The system of tributary trade was implemented in the Ming dynasty. The only ocean-going trade led by Zheng He was organized during the Yongle emperor period to Xuande emperor period. But sea smuggling has been associated with tributary trade since at least the time of Xuande emperor period, and became more and more rampant by the time of the Chenghua emperor. People living in the coastal areas bought foreign goods from the sea and sold them to the inland China. Foreign envoys brought illicit goods into China for trade and then bought a large number of silk goods for export. Emperor Chenghua made new cases based on the prohibition of smuggling issued in Tianshun eight year. The punishment for smuggling trade is stricter than Da Ming Law. However, the phenomenon of smuggling could not be prevented. The government finally opened maritime trade under emperor Longqing period.