Abstract: Soil moisture(SM) is one of the most important factors affecting hydrological processes and vegetation growth, especially in arid and semi-arid areas. This study aimed to investigate the effects of planting density(Chinese pine) on SM and its temporal stability in rocky mountain area of Northern China, which would be conducive to sustainable management of forests. Six plots located on the shady and sunny slopes and with low, medium, high density, respectively, were employed in the study. Soil moisture was measured at 0-20, 20-40, and 40-60 cm in depths. Besides the SM, the temporal stability of the soil moisture of the plots was also analyzed in the term of the index of temporal stability (ITS). It has been found that, on the shady slope, the mean SMs of the soil profile did not show significant difference(P>0.05) between the three planting densities in either wet years(2013) or normal(2014) years. On the sunny slope, the plot with a low density(SUL) had the significantly highest SM(P < 0.05) when compared with the other densities. Significant differences in SM between the middle and the high density plots were only found in 2014. The effect of planting density on SM at each depth did not uniform across the profile. The SM at the sub-surface layer(20-40 cm) and deep layer (40-60 cm) on shady slope plots showed an unexpected increasing trend with the increase of planting density, different from those of the other depths on either shady or sunny slope. It is assumed that the increasing SM trend might be partly due to the increased litters and more throughfall in the high density plots. When the data observations at the three densities were pooled together, It was found that the ITS values of soil moisture were generally positively correlated with the values of SM. However, the effect of planting density on ITS of soil moisture was more obvious on sunny slope plots, with theirs ITS values widely distributed when the planting density changed. Moreover, the mean ITS value of either of the densities on sunny slope was generally higher than that on shady aspect. It may be concluded that, in rock mountain area of Northern China, the increase of planting density would not significantly affect soil moisture and its temporal stability on shady slope plots. However, it did not hold true for sunny slope plots. To implement a sustainable forest ecological management, it is highly suggested to maintain low planting density on sunny slope plots for an effective ecological effect.