Here we demonstrated two different hydrothermal methods for synthesizing Fe3O4/CoSe2 hybrids with different weight ratios of Fe3O4 and CoSe2. The synthesized materials were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. And the electrochemical properties were obtained by linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy. For the first method, the obtained catalyst with loading 20% Fe3O4 on CoSe2 (C20a) exhibits the highest oxygen reduction reaction activity. While for the second method, the obtained catalyst with loading 30% Fe3O4 on CoSe2 (C30b) exhibits the highest oxygen reduction reaction activity, with an onset potential of 0.775 V, a half-wave potential of 0.600 V, and Tafel slope of 65 mV decade(-1) in O-2-saturated 0.5 M H2SO4. Which are better than those of C20a (0.753, 0.567 V and 67 mV decade(-1)), CoSe2 (0.708, 0.560 V and 66 mV decade(-1)) and Fe3O4 (0.700, 0.556 V and 79 mV decade(-1)). More importantly, C30b shows much higher stability and better methanol, ethanol and ethylene glycol tolerance than other prepared materials.