The Tourism industry association is a non-profit organization that is a bridge between the government and tourism companies to maintain the common interests of the tourism industry and members of the association, and to promote the sustainable development of tourism and member companies. The credibility degree to the self-discipline and supervision of tourism industry associations will affect the public’s willingness to spend in member companies of tourism industry association. This paper takes China’s G Hot Spring & SPA Industry Association in China as an example to investigate the credibility in the G Hot Spring & SPA Industry Association and the public’s willingness to spend on the member companies of the G Province Hot Spring & SPA Industry Association, and then analyze the factors affecting the credibility of the Hot Spring & SPA Industry Association. It was found that the public did not have a high degree of trust in the shortlist. The association’s insufficient publicity by the self-media, the imperfect internal governance mechanism of the association, the insufficient of government supervision over the hot spring industry associations, and the imperfection of the social credit system lead to low credibility. Relevant strategies and suggestions to enhance the credibility of the tourism industry association were proposed.