The fabrication of Nano-Au/Porous-TiO2 composite modified glassy carbon electrode (GCE) and its application in the determination of hydrazine were proposed. The morphological characterization was examined by transmission electron microscope and scanning electron microscopy. The Nano-Au/Porous-TiO2/GCE exhibited a wide linear range of hydrazine from 2.5 to 500μM, with a detection limit of 0.5μM at a signal-to-noise ratio of 3 and with a fast response time (within 3s). Furthermore, the reaction mechanism of the hydrazine on the Nano-Au/Porous-TiO2/GCE was explored. The ease of fabrication, high stability, and low cost of the modified electrode are the promising features of the proposed sensor.