There were numerous laws in the Qing Dynasty and they were updated frequently. The Qing court strictly required that all judicial officials judge major cases according to updated laws. Therefore, there was a great demand for the Great Qing Code and other law books among the Qing bureaucracy and the common people. Qing official publishing houses, however, did not provide enough usable law books to officials and private legal secretaries. In this context, commercially printed versions of the Code and other law books flourished and soon dominated the market, making up for the deficiency of imperial and official editions. Commercial publishers in the Jiangnan area actively participated in compiling, printing, and selling the Code and other law books. On the one hand, Jiangnan had a developed commercial publishing industry. There had been thriving commercial publishing business as well as numerous book stores in cities such as Suzhou, Nanjing, and Hangzhou since the Song and Ming dynasties. On the other hand, Jiangnan produced a large number of private legal secretaries, especially in Hangzhou and Shaoxing. Many literati went through years of legal training and became legal secretaries, assisting officials with administrative and legal works. These legal secretaries were true ″legal specialists,″ and many were familiar with the statutes and substatutes in the Code. They became editors, proofreaders, and readers of commercial editions of the Code. Of more than 100 different commercial editions of the Code printed in the Qing Dynasty, most were compiled by those legal secretaries and sold in the bookstores in Jiangnan. Influential legal secretaries, such as Wan Weihan and Wang Youhuai, participated in compiling and publishing the Code and a large number of law books.  Commercial legal books printed in Jiangnan were sold in various places in the Qing Empire and had a broad readership. Jiangnan commercial editions of the Code did not simply copy the imperial editions. They usually adopted the three-register-per-page printing format. Imperially promulgated laws were printed in the lower registers; private legal commentaries, model cases, and administrative sanctions were printed in the middle registers. A cross index was printed in the upper registers. Jiangnan commercial editions were updated in a timely fashion. They usually included newly-updated substatutes earlier than the imperial editions did. These commercial editions took the place of the imperial editions and became the most important reference books when officials studied laws and sentenced legal cases. Represented by ″Tongzuan jicheng,″ the commercial editions printed in Hangzhou were the best commercial editions in the Qing Dynasty. They were endorsed and recommended by many high-ranking officials and became the most authoritative and popular commercial editions. In the late Qing period, almost all commercial editions copied the ″Tongzuan jicheng″ editions of Hangzhou. Commercial publishers and private legal secretaries in Jiangnan challenged the Qing court’s monopoly in producing and circulating legal knowledge. The Code and other law books were available to more readers thanks to commercial legal publications. Commercial publishing industry in Jiangnan had a huge influence on the production and circulation of legal knowledge in the Qing Dynasty.