在明朝政府严厉的海禁政策之下，朝贡贸易的官方港口宁波港在正德、嘉靖年间逐渐成为走私贸易的大港。其中，对日棉布走私情况值得关注。在16世纪，日本国内的棉布需求量较大，同时中国江南地区棉纺织业的迅速发展，这两个因素共同促成了中日之间的棉布走私贸易。这一时期，宁波港的私人海商集团在棉布走私贸易中扮演了重要的角色，他们的活动促进了明朝的对外政策走向部分开放，但也在一定程度上对沿海民众的生活造成了影响。

Because of the Ming Dynasty's strict embargo policy, Ningbo Port, the official port for tributary trade, gradually became a major port for smuggling trade during the Zhengde and Jiajing reigns. The situation of cotton cloth smuggling to Japan is noteworthy. The high demand for cotton cloth in Japan and the rapid development of the cotton textile industry in the south of China jointly contributed to the smuggling trade of cotton cloth between China and Japan. During this period, private sea merchant groups in Ningbo Port played an important role in the smuggling trade of cotton cloth. Their activities promoted the partial opening of the Ming Dynasty's foreign policy, but also caused some damage to the lives of coastal people to a certain extent.