Today, although much attention is paid to sports, but due to less attention to sports psychology, athletes may suffer consecutive failures. Anxiety is a disruptive factor that affects the performance of athletes. The aim of this study was the investigation of the self-determination intervention effectiveness based on reducing competitive anxiety of male taekwondo practitioners in Isfahan. This research is applied study and pre-test-post-test field researches with control group and random assignment. Participants were selected by convenience sampling method and 30 participants were selected using sports competition anxiety questionnaire and randomly and equally divided into experimental and control groups. First, a pre-test was performed using the Sports Competition Anxiety Questionnaire, then a self-determination package was performed for the experimental group for 12 sessions of 60 minutes. Both groups completed the Competitive Anxiety Questionnaire again after the test. The results of mixed ANOVA analysis of variance test showed that in the experimental group, cognitive anxiety and physical anxiety of male taekwondo practitioners decreased (p<0/05) after using the self-determination training package. Self- confidence also increased (p<0/05). Due to the effectiveness of self-determination training program on reducing anxiety and increasing self-confidence, the use of this training program is recommended to professional athletes and coaches. It is possible that the self-determination package increases the level of action independence and thus reduces anxiety by improving the level of motivation.