Crown architecture is a critical component for a tree to interact with the ambient environment and to compete with neighbors. However, little is known regarding how climate variability may shape crown architecture traits across large geographical extents and whether crown architecture traits have coordinated variations with trunk and leaf traits to climate gradients. Here we used Quercus mongolica trees as an example, used the cutting‐edge terrestrial laser scanning technique to accurately characterize their crown architecture traits, and explored their variabilities along with environmental variability across large climate gradients in northern China. Our results showed that there are significant spatial variations in trunk, crown, and leaf traits even for the same genetic group across large environmental gradients. Tree height and leaf size had tight covariations with precipitation (|R |> 0.8, p < 0.01). We also observed coordinated variations among crown architecture traits related to canopy shape (e.g., primary branch insertion angle, chord length ratio), trunk traits (e.g., tree height), leaf traits (e.g., specific leaf area), and climate variability, highlighting there are likely fundamental evolutionary strategies regulating these covariations. With a projected drier and hotter climate scenario in this region, our results further suggest trees are expected to transit from a “tree shape” to a “shrub shape,” with large ecological and ecophysiological impacts on this region.