Objective To understand the mental and behavioral abnormalities of emergency department (ED) patients in general hospitals, and to provide reference for formulating intervention countermeasures. Methods We designed a module for assessment of mental and behavioral abnormalities and integrated it into the computerized emergency clinical information system, then we assessed 10,522 ED patients. The Modified Overt Aggression Scale, Hamilton Depression Rating Scale, and Hamilton Anxiety Rating Scale were used to confirm screening results. Results A total of 108 patients with mental and behavioral abnormalities were screened, accounting for 1.03%, and the ratio of male to female was 1∶1.12. Those with mental and behavioral abnormalities were mainly detected at two periods of the day, from 10:01 to 16:00 and from 20:01 to 2:00. Forty-two cases (38.89%) showed only abnormal mental state, and 66 (61.11%) had multiple abnormal mental and behavioral manifestations. The incidence of violent aggression in men was significantly higher than that in women, and the incidence rates of suicide/self-injury in women and those who recently had conflicts with the surrounding population were significantly increased (all P<0.05). There were significant differences in incidence rates of suicide/self-injury in patients in different age groups and different emergency stages (both P<0.05). Conclusion ED patients have various abnormal mental and behavioral manifestations. Nursing staff should timely identify and manage, thus to ensure patient and healthcare worker safety.