Scarce active sites and poor electrical conductivity of molybdenum diselenide (MoSe2) impede its practical application as an electrocatalyst for hydrogen evolution reaction (HER). Addressing these problems, herein, tailoring suitable morphology and introducing metallic 1T phase for the original semiconductive 2H-MoSe2 are adopted. Eventually, the edge-rich 2H/1T-MoSe2 nanoflowers with enlarged interlay spacing were synthesized by using a solvothermal method, where a mixed solvent of water and dimethyl formamide plays a dominating role in regulating the growth of the MoSe2. The resulting MoSe2 electrocatalyst shows enhanced HER activity in 0.5 M H2SO4 in terms of a low overpotential of 250 mV (vs. RHE) at a high current density of 100 mA cm(-2), an acceptable Tafel slope of 62 mV dec(-1) and excellent stability after a 72-h HER process. This work provides an effective strategy in the development of the high-performance MoSe2-based electrocatalysts for the HER and other energy-related applications.