Water is the most important eco-factor which strongly constrains the survival, reproduction, and dispersal of plants in typical steppes. Plants can adapt to arid environments through various water strategies. To elucidate the characteristics of leaf water potential and its relationships with the functional traits of leaves and roots in the typical steppes in Inner Mongolia, we measured the predawn water potential, midday water potential, and functional traits of leaves and roots in 71 plant species during the growing seasons in 2017 and 2018. We had the following key results. The predawn and midday water potential of all the 71 species ranged from -2.67 to 0.63 MPa and from -4.67 to -1.01 MPa, respectively. Among five plant functional groups, the annual plants had the highest predawn and midday water potential, and the smallest diurnal range of water potential (i.e. the difference between predawn water potential and midday water potential); the perennial grasses followed the opposite patterns. The water-adaptive strategies of 71 plant species were quantitatively classified into three types: high water potential type, low water potential type, and fluctuant water potential type. Across 71 plant species, their midday water potentials exhibited significantly negative correlations with their leaf dry matter content and root depths (P<0.01), and significantly positive correlations with their specific leaf area (P<0.01). Our findings might help us to understand the water adaptability and water ecological characteristics of plant species in the typical steppes in Inner Mongolia from the perspective of plant physiology.