In order to deeply explore the temporal and spatial variation characteristics of soil moisture in dunes in semi-arid areas and its relationship with environmental factors, this study selected the Horqin Sandy Land, as the study area. Based on in-situ observation, numerical simulation, and redundant analysis, the temporal and spatial variation characteristics, variability, water balance and quantitative relationship of the environmental factors of soil moisture in dune were studied. The results showed that the soil moisture in the dune shows a trend of a gradual transition from a "mirror S" type of moving sand dunes to an "S" type of fixed dunes, and a "normal distribution" on the time scale. The soil water variability of the semi-flow, semi-fixed, and shady fixed dune gradually decreased with the increase of depth, and the half sun slope fixed dune showed an "S" type distribution with a maximum coefficient of variation of 75.45%, all of which were moderately variable. The water in the semi-flow and semi-fixed dunes was mainly consumed by deep leakage, accounting for 57.35% and 54.56% of the total water, respectively. The half sun slope fixed and shady fixed dunes moisture was mainly consumed in vegetation transpiration, accounting for 77.15% and 54.88% of the total water. The factors affecting soil moisture in dune were different. Bulk density, sand content, silt content, and saturated hydraulic conductivity were the main factors affecting soil moisture in semi-flow, semi-fixed, and shady fixed dunes. However, organic matter, sand content, silt content, and saturated hydraulic conductivity were the main influencing factors of soil moisture in the half sun slope fixed dunes. Study showed that the half sun slope fixed dunes are easy to consume the deep soil water, causing soil desiccation, and herbs and semi-shrubs are conducive to deep soil moisture retention.