Wheat spikes are key organs for yield formation, and their number, morphology, and spatial distribution strongly influence grain-bearing capacity and yield potential. However, under field conditions, spike phenotyping is constrained by severe occlusion and overlap among spikes, leaves, stems, and neighbouring plants, making conventional two-dimensional (2D) imaging and manual measurements insufficient for accurately characterizing three-dimensional (3D) spike structure. Here, we developed an integrated framework for automatic segmentation, trait extraction, and phenotypic analysis of wheat spike point clouds acquired by a gantry-based field 3D laser scanning platform. We proposed 3D Spike Former, a point-cloud segmentation network built on Point Transformer V3, incorporating a Cross Slice Attention Module and a Feature Complementary Mapping module to enhance recognition of fine spike structures, boundary regions, and complex field backgrounds. Based on segmented spike point clouds, multi-scale 3D traits were automatically extracted, including spike number in internal and external rows, global and local uniformity, spike length, width, inclination angle, surface area, and volume. A software package, 3D Spike Trait Analysis, was further developed to support streamlined and visualized spike phenotyping. The framework effectively captured growth-stage-dependent spike distribution, within-plot spatial heterogeneity, and genotypic variation in spike architecture. Extracted traits enabled dynamic variety ranking and phenotypic clustering using principal component analysis, random forest modelling, and hierarchical clustering. Spike length estimates agreed well with manual measurements (R² = 0.912), and 3D Spike Former achieved 91.4% precision. This study provides an efficient field-based approach for 3D wheat spike phenotyping, population structure evaluation, and genetic analysis of complex spike traits.