To overcome the water solubility and aggregation of heteropoly acids (HPAs), and to promote its application in the electrochemical biosensors, organic molecular modification strategy was employed by simple hydrothermal synthesis. Herein, an unprecedented phosphotungstate (PTA)‐based three‐dimensional supramolecular framework with helical structure, [(bix)2(H3PW12O40)·H2O] [PTA‐bix, bix = 1,3‐bis(imidazol‐1‐ylmethyl) benzene], was synthesized and characterized. And the PTA‐bix modified glassy carbon electrode shows the high sensitivity and catalytic activity for detecting the neurotransmitter dopamine (DA) with the linear detection range from 1 μM to 100 μM, and the detection limit of differential pulse voltammetry (DPV) is 0.85 μM. The concept behinds the new architecture to modify electrodes should promote the further development of HPA hybrid crystal material‐based biosensors.