Abstract: Objective: To investigate and study mental health of military college students during school over a period of 4 years. Methods: To select randomly 104 fresh men who had never accepted any psychological training,125 sophomores,114 junior students、 120 senior students who had respectively accepted one year′s,two year′s,three year′s psychological training in some naval academy.They composed four groups,which were assessed by MMPI. Results: The incidence of mental disorder（descended） year by year（respectively 12.5%,10.7%,9.5%,8.5%）for military college students.The average scores of Hs、Pd、Pa、Pt、Sc、Ma、Si、 F、Mas、Dy descended gradually year by year,and there were significant differences among four groups;The average scores of K、DO、Re ascended gradually year by year,and there were significant differences among four groups.（Conclusions: The） incidence of mental disorder of military college students descended year by year;Their level of psychological health ascended year by year;Their personality developed in a good way year by year.