We report the fabrication of highly ordered Nb2O5 nanochannel film (Nb2O5-NCF) onto niobium foil by an anodization method.After thermal treatment,the obtained Nb2O5-NCF with rich oxygen vacancies exhibits electrochemical N2 reduction reaction (NRR) activity with an NH3 yield rate of 2.52 × 10-10 mol cm-2 s-1 and a faradaic efficiency of 9.81％ at-0.4 V (vs.RHE) in 0.1 mol/L Na2SO4 electrolyte (pH 3.2).During electrocatalytic NRR,the Nb2Os-NCF takes place electrochromism (EC),along with a crystalline phase transformation from pseudo hexagonal phase to hexagonal phase owing to H+ insertion.This results in the reduced NRR activity due to the decrease of oxygen vacancies of hexagonal phase Nb2O5,which can be readily regenerated by low-temperature thermal treatment or applying an anodic potential,showing superior recycling reproducibility.