Planting density is a key factor in regulating plant individual growth and population structure. It directly infl uences the morphological construction and spatial distribution of the root system, thereby playing a decisive role in the ecological restoration of the urban relocated site. This experiment included 8 common shrubs planted at the soil improvement site of a typical urban relocation, using a split-plot design (A factor: shrub species; B factor: planting density). The root morphology and spatial distribution characteristics of shrubs were investigated, and the eff ects of planting density on the root growth and the correlation between underground roots and aboveground characteristics were analyzed after 5 years of growth. The results showed that the maximum vertical depth of shrub roots was 50 cm, and the horizontal dimensions were 101 cm (east-west) × 96 cm (north-south). Based on the presence or absence of primary roots, vertical depth, and extended type and basic form, the root systems were classifi ed into primary and fi - brous root types; deep, middle, and shallow root types; and vertical, horizontal, and vertical-and-horizontal root types. The vertical depth of roots increased with planting density, and deep-rooted shrub species were most aff ected. Under high planting density, the east-west and north-south root lengths of 62.5% shrub species were longer than those under low planting density. Planting density aff ected the number of roots and branches at diff erent levels. The root vertical depth was positively correlated with the plant height, root number, and branch number. There was a positive correlation between root depth and plant height, number of roots, and branches. Choosing an appropriate shrub planting density can improve the ecological restoration of an urban relocation site in landscaping.