By taking apple-soybean intercropping system on the loess region of West Shanxi Province as the research object, the soil moisture content, biomass and yield of soybean were tested at different key phenophases. The results indicated that:(1) The soil moisture of apple-soybean intercropping system changed significantly in different phenophases, and the maximum consumption period for soil moisture was the flowering period of soybean. In different phenophases, the main competitive area and the degree of competition for soil moisture between apple trees and soybean were significantly different;(2) In horizontal direction, the soil moisture content increased with increase of the distance from the tree base, and the lowest soil moisture content was the area adjacent to the tree base;(3) In vertical direction, the soil moisture increased with the increase of soil depth in both of the intercropping system and soybean monoculture plots at soybean seedling stage and bearing pod stage. In the flowering stage of soybean, with the increase of soil depth, soil moisture decreased at first and then increased with the increase of depth;(4) Compared with monoculture plots, an overall negative soil moisture effect appeared in apple-soybean intercropping system and resulted in the loss of soybean production. Due to the soil water distribution in different phenological periods of apple-soybean system, the authors recommended that the appropriate regulation and management measures should be taken to alleviate interspecific competition for moisture and to improve soybean yields.