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The dynamic change of stem water content is an important index to study the water content and growth condition of plants, which provides scientific basis for accurately judging the water deficit of active wood, plantation cultivation and irrigation of urban landscaping. Taking the potted crabapple as research object, and the relationship between the change law of stem water content and physiological water requirement of trees was explored through drought stress experiment. Drought stress was divided into two phases, the first phase lasted five days and the second phase lasted ten days. The decrease in stem water content in the second stage was larger than that in the first stage. And the number of leaves withered in the second stage was more than in the first stage. Comprehensively considered the ornamental nature of crabapple, the research took the first stage of drought stress experiment as research node. It was obtained that the stem water and soil water of crabapple showed a one-degree cubic polynomial relationship under natural drought conditions. An irrigation control strategy with stem water content (43%) and stem water content reduction range (12%) as the lower limit index and soil water content (33%) as the upper limit index was proposed. According to the strategy, an intelligent irrigation control system was designed, and the effectiveness and feasibility of the proposed irrigation strategy were verified by the system.