Abstract: Based on the data of daily of meteorological stations (2011-2015) in Guizhou Province and automatic soil water observation station data, the irrigation volume of tomato in the off-season in Guizhou Province was calculated by using the farmland soil moisture balance equation.The spatial distribution characteristics of tomato irrigation volume in the off-season in Guizhou Province and the temporal and spatial variation characteristics of tomato irrigation volume in different planting dates were analyzed.Meanwhile, the Python language was used to carry out EOF analysis on the sowing date with minimum irrigation volume, so as to find out the sowing date and region with minimum irrigation volume, which has a guiding effect on increasing the output of tomatoes in the off-season of Guizhou Province and reducing the cost.