Background: Nowadays, Suicide is a major public health problem in the worldwide, and an important complication of the industrial world. On the other hand, in military forces, suicide is a mental health problem because these groups have familiar with the use of weapons, the high stress level situations, and a distinct situation from the others. Therefore, this study was conducted to investigate the effectiveness of problem solving skills in the adjustment and reduction of suicidal ideation of soldiers. Materials and methods: This study was a semi-experimental study (pre- and post- test with control group). Totally, 500 soldiers at a military barracks that having suicidal ideation were studied, and among them 90 soldiers who have had suicidal ideation were screened and then were randomly divided into two groups (the control group and problem solving group). Both groups were measured twice, once in the pre-test and once in the post-test, finally their rates of suicidal ideation were compered. The problem solving skills was conducted only for treatment groups and control group did not receive any training. Beck’s Suicidal Ideation Scale was used to measure suicidal ideation. The data were analyzed by SPSS software and covariance methods were used. Results: The mean age of experimental group and control group were 23.51± 2.418 and 23.02±2.241, respectively. The groups had no difference in age and education. The results showed that problem-solving skills training is effective in reducing suicidal thoughts in soldiers (p<0.01). In other words, suicidal ideation had a significant decrease in problem solving groups compared with the control group. Conclusion: Problem-solving skills training can be effective in reducing suicidal thoughts of soldiers. It is suggested that the protocol of problem-solving skills be used to raise hopes and reduce thoughts and suicide attempts.