The participatory culture and shared culture in the new media environment have contributed to the prosperity of fanfiction works. The works of the fanfiction refer to new works that authors create based on characters，images，characters，plot in the original works of novels，comics，games，films，TV plays，and so on. There are copyright conflicts between fanfiction creation and original works and some problems in the protection of fanfiction works’ copyrights. This article takes Jin Yong v.Jiangnan’s copyright infringement case as an example to discuss the copyright issues of fanfiction. This article holds that the fanfiction named “There They Were” belongs to non deductive fanfiction works and does not infringe upon the copyright of the original works，such as the right of protection the integrity of the works and the right of adaptation and it can be regarded as fair use. Under the new media environment，fanfiction works are of great value to the prosperity of the cultural market. We should promote copyright protection and take the system and the supervision of the third party to avoid copyright infringement