Water adsorptions on TiO2-terminated SrTiO3（001） surfaces at four kinds of coverages （0.25 monolayer（ML），0.5ML，0.75ML and 1ML） are investigatedby by using density functional theory calculations. Molecular and dissociative adsorptions of water are comparatively investigated. The nudged elastic band method is employed to calculate the dissociative energy barrier. The obtained results showed that dissociative adsorptions were energetically more favourable at low coverages （0.25ML and 0.5ML）， whereas molecular adsorption was more favourable at high coverage （1ML）， and particularly a special mixed adsorption was more favourable at 0.75ML. Based on these results， the influence of adsorption coverage on water dissociation is analyzed.