Because of creating serious problems for patients, schizophrenia has gained many attentions. One method to reduce negative symptoms of schizophrenia patients is mental-social approach. Applied method in this study is semi-pilot method. Statistical population consists of all schizophrenia patients hospitalized in rehabilitation centers of Karaj City by 2015. Out of the population, those with high value in Scale for the Assessment of Negative Symptoms (SANS), 30chronic schizophrenia patients were selected randomly as sample individuals and were placed in two groups with 15 members in each group. Experimental group received 8 sessions of intervention of social skills and control group was in waiting list. Both groups fulfilled the SANS again before and after intervention and 2months after the treatment. Obtained results were analyzed using MANCOVA and SPSS-22. Obtained results from the study showed that there is significant difference between experimental and control groups after training social skills for improvement (p<0.01). Obtained results show that social skill training can affect reduction of negative symptoms.