Hydrogen gas was obtained from organic wastewater by acidogenic fermentation of two-phase anaerobic wastewater treatment process. In this paper, the hydrogen production of mixed acid fermentation was investigated. In mixed acid fermentation, pH value of fermentation was in the range of 4.5~5.0, the COD removal rate was about 20%. The average transferring rate of sugar was about 94.6%. Our results demonstrated that when Organic Loading Rate was 15 kgCOD/m3·d, the specific biogas production rate of mixed acid fermentation was 1834~2392 mmol/(kg∙d), and the average specific biogas production rate was about 2077 mmol/(kg∙d). The specific hydrogen production rate of mixed acid fermentation was about 532~710 mmol/(kg∙d), and the hydrogen content was around 30%. The main liquid products of our experiments in mixed acid fermentation were ethanol, acetic acid and propionic acid.