Hydrogen, as green chemistry and renewable energy, could be applied for a wide variety of renewable energy storage and conversion devices. Therefore, searching for highly efficient catalysts for the hydrogen evolution reaction (HER) is particularly important. In this work, by tuning the molar ratio of Co/Fe, we produced a series of ultra-thin two-dimensional (2D) Co-x-Fe-y-P nanosheets on carbon cloth (Co-x-Fe-y-P/CC) as HER electrocatalysts. The structure of Co-x-Fe-y-P nanosheets directly depends on the amounts of iron incorporation in the Co-x-Fe-y-P, while the optimal amount of incorporated iron motivates the electrocatalytic performance of Co-x-Fe-y-P for HER, i.e. the Co-0.515-Fe-0.168-P exhibits excellent catalytic performance with a small overpotential of 41 mV at a high current density of 100 mA cm(-2), and a Tafel slope as low as 31.5 mV dec(-1) in 0.5M H2SO4. Detailed investigation reveals the obviously increased electrochemically active surface area, faster electrons transfer, and the strong electronic interaction between the heterogeneous elements after incorporating Fe might boost the excellent HER performance.