Reactive oxygen species (ROS) are byproducts of normal plant metabolism and their production is elevated under environmental stresses such as drought, extreme temperature, and salinity. Among these, salinity is a worldwide problem that impacts the fertility of arable lands and sustainability of food security, which is getting more attention due to climate change. Halophytes can survive and reproduce in soils containing high concentrations of salt and have developed adaptation mechanisms at physiological, biochemical, and molecular levels including maintenance of ROS metabolism. In this review, we aim to summarize findings related to ROS production, signaling, scavenging, and especially ROS avoidance mechanisms under salt stress. In addition, expressions of antioxidant genes in Arabidopsis thaliana and its close relative, the model halophyte Schrenkiella parvula, are compared. Moreover, time-course expression levels of genes encoding major antioxidant enzymes in the model plant A. thaliana are analyzed with publicly available data to understand rapid responses of antioxidant defense under salt stress. The role of ROS-Ca+2 interaction and involvement of NADPH oxidases in this process are also discussed in the context of the perception and signaling of salt stress.