The present work is aimed to investigate the effect of heat treatment on corrosion resistance of Al-alloy 7020-T6 in sea water, the specimens which manufactured by (1.5*1.5*0.2) cm, according to ASTM (G31-72)  The heat treatment was carried out at 480°C and water quench after that artificial aging are implemented at temperature 150°C for (1, 4) hours. Microstructure and phase properties after heat treatment and corrosion test were investigated by optical microscope; X-ray diffraction and
computer potentiodynamic polarization technique have been used to study corrosion behavior in 3.5% NaCl. The results of corrosion resistance 7020-T6 decrease by solution heat treatment and, increase the holding time from 1- 4 hour would increase the corrosion rate, Intermetallics compounds containing zinc represent as the sacrificial anode and control pitting corrosion in 7020-T6 alloy also, the artificial
ageing time increase the precipitation of zinc and decrease pitting corrosion at 1 hour.