This study examined the mediating role of alcohol use in the relationship between PTSD symptoms and psychotic reactions. 231 participants including 181 females were recruited via web advertisement and flyers.Alcohol use status, psychotic experience (indicated by hallucination and paranoia specifically), and PTSD symptoms were measured by Feeling the need to Cut down, Annoyed by criticism, Guilty about drinking, and need for an Eye-opener in the morning (CAGE), Psychosis Screening Questionnaire (PSU), and Short screening scale for posttraumatic stress disorder (SSSP). All the participants were asked to fill in the questionnaires on the Internet and were interviewed later to validate the screening. Logistic regression was used to estimate the mediating effect of alcohol use. Results showed that alcohol use played a mediating role between PTSD symptoms and auditory hallucination while this effect didn't exist between PTSD symptoms and paranoia.Findings implicated that hallucination experience related with post-traumatic experience was affected by alcohol use while paranoia was not.