Leaf water potential and soil water potential of Syrah grape was analyzed by three different agronomic measures of grass growing, shading and alternate irrigation, so as to determine the influence of different water potential on product quality and provide scientific basis for timely quantitative irrigation. Taking the wine grape Syrah as the research object under the same conditions within 2 years, the leaf water potential, soil water potential, stomatal conductance and leaf node of Syrah grape before and after the color transformation stage were comprehensively studied by using three measures: planting alfalfa between rows, black sunshade net, single row and double pipe irrigation. Finally, the best agronomic measures were determined based on the physical and chemical indexes and sensory evaluation after harvest. The effect of alternate irrigation was the most significant in leaf and soil water potential, and the quality of raw materials was significantly improved after harvesting. The optimal harvest was achieved when the soil water potential was from -60 to -80 Kpa and the total sugar content of fruit was above 260 g/L.