This paper analyzes the spatial and temporal variety regulation of soil moisture and soil moisture characteristic constants on mobile dune in Horqin sandy land. The research shows that the soil moisture of mobile dune takes on obvious spatial and temporal variety characteristics with the rainfall, withered moisture and mechanical composition present ruleless variety because of the complication of aeolian movement. There exists notable negative correlativity between the field moisture capacity and soil unit weight with the variety of depth. Atthe same time, the quantification of soil moisture characteristic constants provides some theories for controlling and restoring the mobile dune.