The deterioration mechanism of sulfate attack on cement- based materials under partial soaking condition is very complex. This paper investigated the surface morphology, microstructure and corrosion products in different zones of cement mortar under 5% sulfate solution partial soaking condition at 360 d by methods of SEM, EDS and XRD, respectively. Results show that under partial soaking condition, cement mortar are distinguished four zones – soaking zone, wet zone, crystallization zone and dry zone. Corrosion products in soaking zone and wet zone are predominantly ettringite, showing chemical corrosion take place in those zones. Corrosion products in crystallization zone are gypsum and crystals of Na2SO4 and Na2SO4.10H2O, showing both sulfate chemical corrosion in high concentration and physical crystallization attack occur in this zone. However, there is no any corrosion product founded in dry zone.