Waterlogging is one of the major abiotic stresses threatening crop yields globally.  Under waterlogging stress, plants suffer from oxidative stress, heavy metal toxicity and energy deficiency, leading to metabolic disorders and growth inhibition.  On the other hand, plants have evolved waterlogging-tolerance or adaptive mechanisms, including morphological changes, alternation of respiratory pathways, antioxidant protection and endogenous hormonal regulation.  In this review, recent advances in studies on the effects of waterlogging stress and the mechanisms of waterlogging tolerance in plants are presented, and the genetic differences in waterlogging tolerance among plant species or genotypes within a species are illustrated.  We also summarize the identified QTLs and key genes associated with waterlogging tolerance.