Objective: This study examined admission patterns, including voluntary, involuntary, and partly voluntary admissions to Chinese psychiatric hospitals, in relation to sociodemographic and clinical factors, before a new mental health law was implemented in 2013. Methods: Previously admitted patients were interviewed within one week after discharge from 16 psychiatric hospitals across China. Patients' basic sociodemographic and clinical data, including results from the Modified Overt Aggression Scale (MOAS) and the Insight and Treatment Attitudes Questionnaire (ITAQ), were collected. Results: Among 797 patients, 224 (28%) had voluntary admissions, 336 (42%) had involuntary admissions, and 237 (30%) had partly voluntary admissions. Male gender, history of hospitalization, diagnosis of schizophrenia and related disorders, and high MOAS score were the risk factors for involuntary admissions, whereas more years of education, higher ITAQ score, and outpatient treatment before the index admission were its protective factors. A diagnosis of schizophrenia-related disorder and high MOAS score were the risk factors for partly voluntary admission, whereas more education and high ITAQ score were its protective factors. Conclusions: Perception of dangerousness and poor insight about mental illness were significant factors in involuntary psychiatric admissions in China. Factors contributing to the changes in patterns of psychiatric admissions after China's implementation of the mental health law are important topics for further research.