The invention discloses a crape myrtle tree form with a spindly skeleton and a pruning method thereof, which relate to the technical field of garden tree pruning. A trunk of the tree form is obvious, and the trunk is thick and skeleton-shaped, so that an operation of controlling the diameter of a crown, the size of a tree body and the height of the trunk according to the growth space is facilitated; branches are distributed uniformly, a state that lower branches are sparse and upper branches are dense, outer branches are sparse and inner branches are dense, and the branch trend is mean and robust is kept, branches are well-arranged, and a certain distance is kept between layers; the ventilation and light transmission properties are good, thereby facilitating the robust growth of plants, and reducing plant diseases and insect pests; and inflorescences inserted in the periphery of a crown in the flowering period are easy to form a neat bulk structure, the pruning method is simple to operate, easy to carry out, and applicable to the standardized production and management of nurseries, and facilitates the highlighting of a crape myrtle landscape effect in case of being applied to gardens, therefore, the pruning method is suitable to be promoted and applied in garden production.