In this study, we prepared a potentiometric dopamine biosensor based on copper oxide (CuO) thin films modified with tungsten trioxide nanoparticles (WO 3 NPs). We used the excellent anti-interference ability of WO 3 NPs to modify CuO thin films. And the differential pair system is used to measure, and the measurement content includes linearity, sensitivity, response time, and interference influence. The sensor of this research project has the advantages of simple structure, easy manufacture, low cost and small volume.