Changes in leaf traits and their trade-offs are reflections of how plants use resources, as well as their adaption strategies to environmental changes. Drought is acknowledged as one of the greatest threats to the growth and development of plants worldwide, and leaves are one of the most drought-sensitive parts of a plant. At present, the effects of drought on leaf traits have been widely studied; however, the trade-off growth between different leaf traits during the progress of drought is less studied, which limits the understanding of plant adaptation strategies in the arid environment. Maize is one of the leading crops in the world, although it is also the most susceptible to drought. Understanding how leaf traits of maize change during the progress of drought and their trade-off growth would help promote the understanding of the adaptation strategies of maize plants to drought and contribute to the development of targeted drought-resistant and drought-relief measures. Therefore, based on the consecutive drought simulation experiment having six primary soil water levels for maize that was conducted in 2014, we investigated changes in five key leaf traits of maize. These were green leaf area, leaf dry mass, specific leaf weight, leaf water content, and effective leaf number, as well as the trade-off growth between the green leaf area and effective leaf number, green leaf area and specific leaf weight, leaf dry mass and leaf water content, respectively. In addition, we developed an indicator to quantitatively evaluate the degree of drought, which consisted of available soil water content, readily available soil water content, and drought duration time, and comprehensively involved factors that were related to the intensity and progress of the water deficit, such as soil texture, meteorological environment, and plant water requirement, among others. Based on this indicator, we quantitatively characterized these leaf trait changes and their trade-off strategies under different drought degrees. The results showed that every leaf trait was affected by drought, however, the extent to which they were affected was related to the degree of drought. The leaf traits were not significantly affected when the degree of drought was below 0.21, and their quantities were affected, although their tendencies were not when the degree of drought was 0.21-0.76. When the degree of drought increased to 0.76-0.91, the effective leaf number, dry mass of leaf, green leaf area, and leaf water content decreased prematurely because the growth of new leaves failed to compensate for the losses caused by senescence of old leaves. When the degree of drought exceeded 0.91, stagnation in leaf growth occurred, and leaf traits barely changed. The adaptive growth of leaves under drought embodied the trade-off between rapid growth and survival, which varied with the degree of drought. Maize maintained high metabolic activity of its leaves until the degree of drought was greater than 0. When the degree of drought was below 0.48, maize tended to grow rapidly by investing more resources into leaf expansion so that more energy could be absorbed. When the degree of drought exceeded 0.48, maize conserved its resources for survival by maintaining relatively lower metabolic activity and smaller leaf size to minimize water loss.