The purpose of this study was to investigate the mediating effect of sport involvement on sport motivation and characteristics of mental toughness in Taiwanese table tennis players with physical disabilities. The sample players were selected from the Taiwan physical disabilities table tennis open. A total of 180 questionnaires were deployed, and 167 of them were returned effectively (97.78%). Results indicated the positive association of sport motivation with sport involvement and characteristics of mental toughness. Sport motivation would directly affect the characteristics of mental toughness, and it would indirectly affect the characteristics of mental toughness though the sport involvement. Therefore, Players with higher sport motivation and sport involvement would have higher characteristics of mental toughness, and sport motivation would indirectly affect the characteristics of mental toughness though the sport involvement. Sport involvement acts as the mediation role in cause and effect mode.