Objective To investigate the influencing factors of duration of untreated psychosis（ DUP） in patients with mental disorders. Methods "Diagnostic and Statistical Manual of Mental Disorders"（ DSMIV） was used as the diagnostic criteria， "DSM-Ⅳ axis Ⅰ disorder with clinical definite examination"（ SCID-Ⅰ/P） as a diagnostic tool. The screened psychiatric patients were investigated with a self-designed "Hebei Mental Health Service Utilization Checklist". Results Totally 252 patients have been diagnosed among 1 826 screened psychiatric patients， and DUP was 15（ 4， 30） days. The patients were assigned into short DUP group（ DUP≤ 15 d） and long DUP group（ DUP＞15 d）， with 149 and 103 cases respectively in the two groups. The comparison of the two groups showed that there was significant difference of the nature of the account（ χ2=4.123， P=0.032）， being diagnosed with chronic diseases by doctors in recent 6 months（ χ2=12.091， P＜ 0.01）， the distance from residence place to the nearest mental health organization（ χ2=24.867， P ＜ 0.01）， whether received health education on prevention and treatment of related diseases before the discovery of mental illness（ χ2=4.223， P=0.040）， whether the first visit medical institution was special hospital（ χ2=4.449， P=0.035）， the first intervention taken when symptoms appeared（ χ2=21.431， P ＜ 0.01）. Logistic regression analysis showed that being diagnosed by doctors in recent 6 months was risk factor（ OR=4.950， 95%CI=1.805-9.291）. Another risk factor of DUP was rural household（ OR=2.041， 95%CI=1.021-3.973）. Conclusions The influencing factors of DUP should be considered in different aspects. Among them， chronic diseases and rural household have a great impact on the DUP of patients.