This article summarizes the current status of artificial intelligence for the protection of intangible cultural heritage, analyses functional expansion of generative artificial intelligence in the protection of intangible cultural heritage in public libraries. It puts out the "implicit" risks faced by generative artificial intelligence in promoting the protection of intangible cultural heritage in public libraries, including the reversal of subject and object status, ambiguity of intellectual property rights, and reconstruction of interest patterns. The article proposes risk prevention paths for generative artificial intelligence to promote the protection of intangible cultural heritage in public libraries from four levels: order concept, order principle, order design, and risk prevention, namely, focus on the development concept as the core to achieve the expansion of intangible cultural heritage protection functions, realize bottom line protection following the principles of minimum restriction and maximum promotion, value alignment, and partial fault tolerance, and collaboratively construct software and hardware laws to establish a flexible governance system for intangible cultural heritage protection, and establish risk prevention mechanism to avoid the infringement risk in intangible cultural heritage protection.