[Objective] We aimed to quantitatively assess the soil water deficit under vegetation in the semiarid loess hilly region in order to provide theoretical support for the selection of vegetation types and ecological restoration pattern.[Methods] The compared soil water deficit index(CSWDI) and plot compared soil water deficit index(PCSWDI) of Caragana korshinskii, Populus simonii Carr and Pinus tabulaeformis in soil profiles of 0-600 cm deepth were calculated to quantify soil water deficit and its profile distribution under different vegetation types on April, May, June and July in Wuzhai County, Northwestern Shanxi Province.[Results] Soil water deficit appeared in all three artificial forestland. Soil water deficit was found in P. simonii and C. korshinskii in soil layers between 0 and 200 cm, however, it was hardly found in P. simonii between 200 and 600 cm. Below 200 cm, soil water deficit increased with increasing CSWDI in C. korshinskii. The P. tabulaeformis had led to a serious deep soil desiccation, especially in soil layers from 0 to 200 cm. Soil water deficit decreased in the layers below 200 cm with the increase of soil depths in P. tabulaeformis. PCSWDI of C. korshinskii, P. simonii and P. tabulaeformis was 0.16,-0.12 and 0.31, respectively. The soil water deficit of P. tabulaeformis was more severe than that in the others two forestland. The dried soil layer was distributed in all three artificial forestland with a different degree, mainly for mild and moderate dry layer distribution. Extreme dry layer presented in shallow soil of P. tabulaeformis.[Conclusion] The soil water deficit in the P. tabulaeformis was the severest among the three artificial forests in the loess hilly regions.