[Objective] Precipitation is the main source of soil water in arid and semi-arid regions. By combining field observation and model simulation to study the regularity of rainfall infiltration, the soil water deficit can be mastered more systematically. [Methods] Through fixed point observation, the Hydrus-1d model was applied to simulate the dynamic change of soil water in Platycladus orientalis on the artificial of Nanshan Mountain in Lanzhou, evaluate the applicability of the model in arid region, and analyze the soil water response and infiltration mechanism under different rainfall conditions. [Results] The Hydrus-1d model had good applicability in the artificial side of Nanshan in Lanzhou, and the deep simulation effect was better. When the rainfall was less than 30 mm, the soil moisture content at 10 cm has the strongest response to rainfall, while the influence of rainfall at 30 and 50 cm was relatively small and had an obvious lag, and there was no response below 70 cm. There was a wetness peak when the rainfall was more than 8.2 mm. During the simulation period, the maximum infiltration depth was 70 cm and the maximum infiltration volume was 23.7 mm. The infiltration depth increased with time, while the infiltration volume and infiltration rate decreased with time. Rainfall was positively correlated with infiltration volume, infiltration depth and infiltration rate (p＜0.05). When the rainfall was less than 20 mm, the rainfall intensity had a significant effect on the infiltration amount, infiltration depth and infiltration rate. [Conclusion] The Hydrus-1d model can be used to simulate the dynamic change of soil water in Platycladus orientalis on the artificial of Nanshan in Lanzhou and calculate the infiltration amount, infiltration rate and infiltration depth. Moreover, it is found that the rainfall has a more significant effect on the soil water infiltration process.