Nowadays, crop insufficiency resulting from soil salinization is threatening the world. On the basis that soil salinization has become a worldwide problem, studying the mechanisms of plant salt tolerance is of great theoretical and practical significance to improve crop yield, to cultivate new salt-tolerant varieties, and to make full use of saline land. Based on previous studies, this paper reviews the damage of salt stress to plants, including suppression of photosynthesis, disturbance of ion homeostasis, and membrane peroxidation. We have also summarized the physiological mechanisms of salt tolerance, including reactive oxygen species (ROS) scavenging and osmotic adjustment. Four main stress-related signaling pathways, salt overly sensitive (SOS) pathway, calcium-dependent protein kinase (CDPK) pathway, mitogen-activated protein kinase (MAPKs) pathway, and abscisic acid (ABA) pathway, are included. We have also enumerated some salt stress-responsive genes that correspond to physiological mechanisms. In the end, we have outlined the present approaches and techniques to improve salt tolerance of plants. All in all, we reviewed those aspects above, in the hope of providing valuable background knowledge for the future cultivation of agricultural and forestry plants.