Objectives The aim of this study was to find out the psychological changes associated with internet addiction between before and after the military drill among the young male army recruits. Methods All 1091 participants were army recruits aged from 19 to 22 years who participated in the 5-week military drill. They were assessed with some self-reported questionnaires [Sociodemographic questionnaires, Young's Internet Addiction Scale (IAS), the State-Trait Anxiety Inventory (STAI), the Beck Depression Inventory (BDI), the Barratt Impulsiveness Scale (BIS), the Attention-Deficit/Hyperactivity Disorder Self-Rated Scale (ASRS)]. They were divided into two groups, One is the internet addiction tendency group and the other is non-addiction group according to the IAS score. And the severity of the internet addiction tendency, depression, anxiety and impulsiveness were evaluated by the IAS, the STAI, the BDI, the BIS, the ASRS before and after military drill. Results The result of the paired t-test shows that the IAS, the STAI, the BDI, the BIS, the ASRS scores decreased after military drill in both non-addiction group and internet addiction tendency group. The result of the repeated measures ANOVA shows that there is an interaction effect between the changes of ASRS-hyperactivity (F = 23.437, p < 0.001), ASRS-impulsiveness (F = 4.896, p = 0.027), BIS-total (F = 4.057, p = 0.044), BIS-motor impulsiveness (F = 13.609, p < 0.001) scores and groups. The result of the generalized estimating equation shows that internet addiction tendency is associated with ASRS-inattention (${\beta}=0.075$, p < 0.001), ASRS-hyperactivity (${\beta}=0.092$, p = 0.002), STAI-trait anxiety (${\beta}=0.046$, p < 0.001), BIS-motor impulsiveness (${\beta}=0.119$, p = 0.028). Conclusions The results show that psychopathologies such as internet addiction tendency, depression, anxiety, impulsiveness may improve after military drill regardless of the groups. Internet addiction tendency may be related to the ASRS-inattention, ASRS-hyperactivity, STAI-trait anxiety, motor-impulsiveness. So these findings may be considered in the treatment of internet addiction in terms of the impulsiveness control.