The most notable effects of drought are manifested in regional-scale forest mortality events, which can kill millions of trees in a short time, further affecting regional climate and ecosystem structure and function. Given that the frequency and intensity of extreme drought events in the future may increase with increasing temperature, it is urgent to clarify the response strategies of trees to drought stress and the mechanisms of their survival and death, reveal the physiological mechanism of woody plants in arid environment, understand the adaptation mechanism of trees in future climates, and improve the accuracy of predicting the response of trees to drought stress. Plant functional traits refer to the morphological, physiological, or phenological characteristics of plants at the individual level, which indirectly affect the performance of plants by directly affecting the growth, survival or reproduction of plants, and at the same time reflect the long-term adaptation of plants to the growth environment. Plant functional traits and their variation regulations can be used to explain the adaptive mechanism and functional optimization mechanism of plants to the environment, and help to predict the response of trees to drought. Compared with commonly used plant functional traits, hydraulic traits may better describe the response of trees to drought stress. On the basis of common plant functional traits, we increased the hydraulic traits which are related to water transport capacity and drought tolerance and systematically summarized: 1) the physical mechanism of long-distance water transport in xylem; 2) phases of drought stress and the response of plants; 3) plasticity in plant functional traits and water regulation strategies: Isohydric regulation strategy and anisohydric regulation strategy, xylem efficiency-safety trade-off strategy, conservative water use strategy and risk-taking water use strategy; and 4) mechanisms of drought-related mortality: hydraulic failure hypothesis, carbon starvation hypothesis and biotic agents hypothesis. Finally, three main problems were put forward to be solved: 1) strengthening the inclusion of hydraulic traits to clarify the response and regulation mechanism of plants to drought stress, understanding and predicting plant survival, growth, distribution and death in the context of global change. 2) strengthening the consideration of the relationship between different plant tissue traits from the perspective of the whole plant, revealing the distribution characteristics of plants in the ecosystem, and predicting community composition; 3) the precise physiological mechanism behind tree death is still unclear, future studies need to further explore the mechanisms of drought-related mortality.