This research expects to develop a hydrogen peroxide detector which fast detect and carries easily, and applies in analyzing the hydrogen peroxide concentration after Fenton reaction. First, we used the Purssian blue as a catalyzer to decrease the detection potential of hydrogen peroxide to hope to avoid the reference in electrochemistry. The screen printed technology owns many advantages such as fast, stable, accurate and low cost. For electrochemical detector, the Prussian modified electrode was fabricated by screen printed technology. The modified electrode was application to detect the concentration of hydrogen peroxide in environment wastewater, and demonstrated the relationship between COD and the concentration of hydrogen peroxide.