The work aims to study a treatment of offset printing ink wastewater by photocatalytic oxidation process, so as to achieve the standard discharge of the offset printing ink wastewater. First, the offset printing ink wastewater was pretreated by coagulation method to reduce the turbidity. Then, the offset printing ink wastewater was degraded by photocatalytic oxidation process and the optimal conditions for such treatment were explored. When the mass concentration of catalyst was 0.4 g/L, UV-light radiation time was 40 min and pH value was 5, the degradation of offset printing ink wastewater by photocatalytic oxidation process was optimal, with COD and chroma removal rate of the offset printing ink wastewater respectively reaching 90.3% and 93.4%. The photocatalytic oxidation process used to treat offset printing ink wastewater is feasible and conforms to the requirements of green printing.