Objective: To explore the effect of K correction on the profile of MMPI in different mentally disordered patients.Methods: First,analyze the correlation of the five basic scales with and without k score.Second,compare means of T scores of five basic scales in schizophrenia group(n=110),affective disorder group(n=106),neurosis group (n=36)and control group(n=64).Finally,explore the effect of K score on T scores of the five basic scales in the three experimental groups and normal group. Results: The mean of the five basic scales in schizophrenia group were significantly higher than those T scores without adding K score.In the affective disorder group Hs,Pt and Sc were significantly altered.In theneurosis group ,Sc and Ma were significantly altered.Only Hs was significantly altered in the control group.When K was lower or higher level,T scores of three experimental groups and normal group were significantly affected. When K was moderate in magnitude,only Hs,Pd and Sc were significantly changed. Conclusion: In clinical applications, the addition of K score has positive values.