The aim of the present study was to investigate the effect of a mental skills training course on psychological flexibility, Anxiety of injury and shooting performance. This study was conducted with a pre-test and post-test design, along with a control group. 52 third-year students of Imam Ali (AS) Officers' University were selected through random sampling and divided into two equal groups, including mental skills training and control. The training protocol consisted of 14 sessions, of which 2 sessions were allocated to pre-test and post-test. In the intervention sessions, mental skills training and practice were conducted based on training instructions. Psychological flexibility was measured with the Lis-Jol et al. (2020) questionnaire and injury anxiety with the Cassidy questionnaire (2006); scores obtained by students in the shooting range were also used to assess shooting performance. The normality of the data was examined using the Shapiro-Wilk test. In the inferential analysis of the data, after ensuring that the assumptions of parametric statistics were met, a 2×2 between-within-group mixed analysis of variance test was used in SPSS version 26 at a significance level of 95%. Graphs were also drawn with GraphPad version 9. The results indicated that mental skills training reduces injury anxiety, improves psychological flexibility, and shooting performance. Therefore, it is suggested that mental (psychological) skills training should be included in the agenda in addition to technical and functional skills in order to improve cognitive skills and control intervening variables.