The temporal and spatial dynamics of soil moisture of flue-cured tobacco were studied by lysimeter experiment. The results indicated that in the growing period of tobacco plant, changes of soil water contents within 0 to 20 cm depth layers was the most significant, but followed by layers within 20 to 40cm depth and it was the most stable within 40 to 60cm depth. In addition, mathematical models describing the changes of soil water contents with time within 0 to 20 cm, 20 to 40 cm, 40 to 60 cm depth were also proposed, with which the temporal dynamics of soil water in flue-cured tobacco could be predicted. Also, it was good that irrigation calculating wetness depth was 20 to 30 cm at the root extending stage, 50 to 60 cm at the vigorous growing stage and 30 to 40 cm at the maturing stage; and the optimum relative soil water combining was better than others when it was at 60%-80%-70% or 60%-80%-60%.