The number and conductivity of active sites of electrocatalysts have become the main factors for excellent performances for hydrogen evolution reaction (HER). In this work, in situ formation of ultrathin C3N4 layers coating on the surface of metallic WO2 nanorods (WO2@C3N4) as electrocatalysts for HER has been realized by a facile dopamine (PDA) coating on WO3 nanorods precursor and following calcination process. Firstly, the uniform polydopamine (PDA) layer has been coated on the surface of WO3 nanorods (WO3@PDA) through a hydrogen thermal process. The ultrathin C3N4 layers with large graphitization degree after calcination of WO3@ PDA can improve the conductivity and stability of catalysts during HER. The formation of one dimensional WO2 nanorods may expose more active sites for HER. Benefited from the synergistic effect between WO2 and C3N4 layers as well as the protection cap of ultrathin C3N4 layers, the obtained core-shell structured WO2@C3N4 nanorods exhibit excellent HER performances and high durability in acidic solution, which only require an overpotential of 98 mV to generate a current density of 10 mA cm(-2). Therefore, this work provides a new strategy for constructing transition metal oxides electrocatalyst with high activity and stability by introducing ultrathin C3N4 layer coupled with 1D nanostructure.