Two dimensional (2D) transition metal dichalcogenides have attracted intense potential application in catalytic because of its fantastic physical and chemical properties. But, how the metal oxide affects the catalytic performance of transition metal dichalcogenides was not clear yet, which always exists as main byproduct in the synthesized process of hydrothermal method. Herein, we report synthesis of 2H-MoSe2 nanoflower and 2H-MoSe2/alpha-MoO3 heterostructure by hydrothermal method. The chemical composition, morphology and crystalline structure of nano-composite were characterized by field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HR-TEM), Xray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The 2H-MoSe2 nanoflower shows more positive onset overpotential around 150 mV and a current density of 32.5 mA cm(-2) at -300 mV. The smaller Tafel slope of 2H-MoSe2 nanoflower is around 69 mV dec(-1) reveals the Volmer-Heyrovsky mechanism for HER. The results of linear scan voltammetry (LSV) curves demonstrated that both of them displayed good stability. This work demonstrated that the metal oxide can reduce the catalysis performance of transition metal dichalcogenides towards HER. (C) 2016 Elsevier Ltd. All rights reserved.