Wastewater from pulp and paper mill is one of the most important sources of pollutants mainly due to the pulping and bleaching processes. This study evaluates the effectiveness of photo-Fenton`s process in reducing organic and suspended solid in pulp and paper mill wastewater. The photo-Fenton`s process produces the strongest oxidation and consumes lower Fe2+ compared to the conventional Fenton`s process. The conditions of the photo-Fenton`s process were optimized such as the initial pH, the H2O2 concentration and the FeSO4.7H2O concentration. It was found that the optimal pH for Fenton`s process was pH 5. The optimal initial concentration of H2O2 and FeSO4.7H2O were 500 and 400 mg L-1, respectively. The overall efficiency of BOD3 and TSS reduced by the Fenton`s process under optimal conditions attained up to 87.5 and 87.0%, respectively. Thus, the photo-Fenton`s process has the potential to be used in the treatment of pulp and paper effluent.