Purpose: This study explored the experiences and learning needs of sport nutrition for fitness instructors when providing sports nutrition advices. Methods: Qualitative design was adopted with semi-structured in-depth interviews in present study. With purposive sampling, seven fitness instructors who possessed at least one-year experience and had given sport nutrition advices were invited to participate in this study. Fitness instructors who had not engaged in fitness instruction for more than five years were excluded from this study. The interviews were conducted during September 2017 and March 2018, and each participant received 1 to 2 interviews with an interview guide. The interview data were recorded, and the feelings and experiences stated by the participants were transcribed verbatim after interview. With thick description, the data were analyzed by content analysis method. Principles of credibility, transferability, dependability and confirmability were adhered for ensuring rigor in this study. Results: The participating fitness instructors perceived they were capable of responding to the clients’ basic sport/exercise nutrition questions with ease. In terms of learning needs, the instructors expressed they would like to possess sport nutrition knowledge that could help clients with special needs, with daily dietary exchange, and with the updated popular nutritional issues relates to sports. The fitness instructors also expressed that they would like to obtain persuasive communication skills, and to learn all the sport nutrition knowledge with approaches that could make the knowledge with flexible use. Conclusion: Although most fitness instructors stated they were able to provide answers to clients’ questions regarding sports nutrition, there are learning needs required regarding persuasive communication skills and specific sports nutrition knowledge. The fitness instructors also expected to possess knowledge in ways that are more practical and flexibility. It is recommended that fitness instructors’ learning needs and adult learning attributes should take into account when designing fitness instructor training course.