Abstarct: Nowadays, sport nutritionists and physiologists study and evaluate the factors which are affecting the health and Practice of athletes. Exercise can have positive effects on the athlete when the athlete's nutritional needs are met and the athlete has sufficient knowledge about them. Therefore, examining the nutritional knowledge, attitude and Practice of athletes in different disciplines can provide basic information for professionals to make effective decisions. In this study, due to COVID19 situation and reduced access to athletes, 100 crossfit athletes in Mashhad were purposefully selected and completed a questionnaire containing demographic information, knowledge, attitude and nutritional Practice and then using SPSS software has been analyzed at a significant level. 82% and 95% of the study participants had moderate knowledge and attitude and 54% had poor Practice, respectively. It can be said that 73.3% of the people who had high awareness and also all the people who had good Practice were women. There is a statistically significant relationship between attitudes and nutritional Practice and education so that it can be said that most people at different levels of education have moderate nutritional attitudes and 76.5% of people with poor nutritional Practice have been skilled. There was a statistically significant positive relationship between age and knowledge and nutritional Practice, while no significant relationship was observed between age and attitude of crossfit athletes. A significant positive relationship was observed between the nutritional knowledge and attitude of crossfit athletes, so that with the increase of participants' awareness, their attitude also increased, while there was a significant relationship between nutritional awareness and Practice and nutritional attitude and Practice. It seems necessary to increase the awareness of athletes through training classes, consultation with nutritionists.