The influence of three main components of environmental-friendly no-clean flux (activator，surfactant and inhibitor)on its corrosivity was studied.The effect of different components on the copper electrode inhibition performance was studied by using alternating current（AC）impedance.The surface corrosion of three main components on comb patterns was also observed with scanning electron microscope，and the residue of flux and interaction were tested by thermal analysis.The results showed that the structure and acidity of the activator had some effect on the corrosivity of the flux.The weaker the acid

the weaker the corrosivity of the flux.The corrosion inhibition of the flux could be improved by the addition of polyoxyethylene nonyl phenyl ether as nonionic surfactant.With benzotriazole (BTA)as inhibitor，the corrosion inhibition performance of the flux was promoted effectively.The results showed that the no-clean flux，using polyoxyethylene nonyl phenyl ether (50)(w=0.2%)as surfactant，showed lower surface tension and better wetting properties.The mixture of succinate and malic acid (w=1.6%)as activator could help to increase the activity of flux.The welding plate expressed less corrosivity after soldering.The flux using BTA as corrosion inhibitor (w=0.06%) showed optimum corrosion inhibition performance，with high membrane resistance and lower inhibition on hydrothermal condition.The mechanisms of this action were discussed by thermal analysis，which showed that the esterification reaction between organic acid and glycerol may play an important role for corrosion inhibition performance improvement in the welding process.