It is very important to develop point-of-care (POC) testing method of dopamine (DA) in human tissue to help the diagnosis and treatment of the diseases such as Parkinson and Depression. Fortunately, carbon nanotechnology offers an opportunity to solve this problem. In this paper, graphene nanoplate/carbon nanotubes (GNP/CNT) nanocomposite screen-printed electrodes (SPE) has been developed with a unique waterborne carbon nanocoating technology. The resulting GNP/CNT SPE has a linear DA detection range from 0.4 μM to 40 μM with differential pulse voltammetry (DPV) method, with an excellent anti-interference to the ascorbic acid (AA) and urea (UA). As a result, DA in human serum can be measured with POC testing strategy. The excellent sensing mechanism are proved to be the high electrical conductivity and the large specific surface area of carbon space network structure of CNT connected GNP; high diffusion rate of DA driven by electrostatic attraction and the oxidative catalytic activity based on the pi-pi interfacial interaction between GNP/CNT electrode and DA.