The purpose of this paper is to investigate the factors that can affect customer satisfaction of Fiber-To-The-home (FTTH) Services of Viettel in Thanh Hoa city. Data from the study were collected from 360 customers using the Viettel FTTH Services. The study results showed that the factors affecting the FTTH Services of Viettel in Thanh Hoa city including: Reliability, Tangibles, Convenience, Service prices, Promotion policies and the Staffs. In which, Reliability is the factor that has the strongest influence on customer satisfaction. The second strongest factor influencing customer satisfaction is Tangible factor, the following factors are: Promotion policies, Service prices, Staffs and Convenience. All factors have a positive impact on customer satisfaction. The authors proposed some solutions to improve customer satisfaction about FTTH service of Viettel in Thanh Hoa city in the next time.