•The micro-pit structure formed on the IN718 surface is the main influencing factor for the surface quality enhancement.•The corrosion behaviour of the IN718 was investigated by electrochemical techniques in C6H5K3O7 solution.•The ligand structure in C6H5K3O7 solution dramatically beneficial to eliminate the electrolytic products in ECM.•The reaction mechanism and quantitative corrosion model of the IN718 were discussed in ECM using C6H5K3O7 solution. The mechanism by which electrolytic products are removed during ECM of Inconel 718 in a C6H5K3O7 electrolyte was clarified. Experimental results revealed that Cit3− ions decrease the amounts of flocculent and insoluble products in the machining region considerably. The resulting passivating film presented a looser, more porous structure than that from a NaNO3 solution. This made the Inconel 718 more prone to electrochemical corrosion. The uniformity and microscale nature of the micro-pit structure dispersed on the machined surface improved substantially as the current density increased. This improved the surface quality dramatically. Finally, the anodic dissolution characteristic models were established.