Objective The current study aims to find out the potential reasons why most schizophrenia patients have a relatively low sensitivity to the classification of emotional facial expressions. Methods By using an emotional categorical perception task, eighty-three schizophrenia patients and seventy-one healthy adults are provided with morphed emotional continuums with two emotional facial expressions (a positive emotional valence: happy; a negative emotional valence: sad). Results Through comparing the difference between schizophrenia patients and healthy adults in the processes of estimating facial expressions with ambiguous emotions, we find that the pattern of emotional categorical perception for schizophrenia patients is significantly different from that of healthy controls when they process signals on the local facial areas. Compared to healthy people, schizophrenia patients have a significantly separate classification pattern in processing emotional signals between the eyes and mouth regions. It indicates that compared to healthy adults, schizophrenia patients have larger conflicts in integrating emotional signals from different facial areas. To overcome conflicts, more cognitive resources are required. Unfortunately, the lack of cognitive resources leads to the failure of integration, which further increases the difficulty of estimating facial expressions with ambiguous emotions, and finally leads to the relatively low sensitivity of emotional facial expressions classification. Conclusion To sum up, the deficit of abnormal perceptions of emotional facial expressions in schizophrenia patients results from an integrated deficit of signals on facial areas.