Hydrogen is one of the most attractive renewables for future energy application,therefore it is vital to develop cost-effective and highly-efficient electrocatalysts for the hydrogen evolution reaction(HER)to promote the generation of hydrogen from mild methods.In this work,Co-Mo phosphide nanosheets with the adjustable ratio of Co and Mo were fabricated on carbon cloth by a facile hydrothermal-annealing method.Owing to the unique nanostructures,abundant active surfaces and small resistance were achieved.Excellent electrocatalytic perfor-mances are obtained,such as the small overpotential of～67.3 mV to realize a current density of 10 mA cm-2and a Tafel slope of 69.9 mV dec-1.Rapid recovery of the current response under multistep chronoamperometry is realized and excellent stability retained after the CV test for 2000 cycles.The change of electronic states of different elements was carefully studied which suggested the optimal electrochemical performance can be realized by tuning phosphorous and metal interactions.