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Ecological environmental worsening and water-soil loss occur frequently in mountainous areas in recent years. As an important index of land deterioration and degree of drought, soil moisture can influence vegetation growth, hydrological cycle and water resource distribution in mountainous areas significantly. However, topographic effect of soil moisture under complicated mountainous terrain conditions still remains unknown. In the present study, a quantitative inversion on surface soil moisture content in a typical mountainous area of Dengfeng city, Henan province (China) in 2013 and 2017 was carried out by using temperature vegetation dryness index method based on Landsat-8 OLI (Operational Land Imager) remote sensing images and digital elevation model (DEM). Results were conducive to analyze effects of terrain factors on spatial-temporal distribution of soil moisture and improve ecological environment in mountainous area. Besides, a quantitative analysis on topographic effect (e.g. elevation, slope and slope orientation) on soil moisture in mountainous area was performed based on DEM data. Results demonstrate that topographic factors (e.g. elevation, slope and slope orientation) can cause violent variations of soil moisture in mountainous areas. Soil moisture is positively correlated with elevation and slope. In view of slope orientations, shady slope generally presents the highest soil moisture, followed by semi-shady slope, sunny slope and semi-sunny slope successively. In 2017, the heat island effect in the study area is stronger and the arid area is significantly larger than those in 2013. Additionally, soil moisture in the region with elevation lower than 750 m and slope smaller than 25° is lower in relative to that in 2013, but it is higher in the region with elevation higher than 750 m and slope larger than 25°. This study discloses the influencing law of terrain factors on spatial-temporal distribution of soil moisture in mountainous areas. Research conclusions provide some scientific references to water conservation and ecological environmental protection in mountainous areas. [ABSTRACT FROM AUTHOR]