To address the unclear classification and genesis of fractured reservoir bodies (FRBs) in tight sandstones of the fourth member of the Upper Triassic Xujiahe Formation (Xu 4 Member), Sichuan Basin, this study integrates field outcrops, cores, well-log–seismic data, production data, calcite U-Pb dating, and fluid-inclusion temperature–pressure constraints to characterize their geometry, formation mechanisms, and temporal evolution. The results show that fractures in the Xu 4 Member are predominantly tectonic and jointly controlled by multi-stage, hierarchical faults and related folds. Three FRB types are identified: fault-fracture-type FRBs, fold-fracture-type FRBs, and fault-fold-fracture-type FRBs. Fault-fracture-type FRBs were mainly formed by early low-order faulting and occur in proximal fault damage zones. They show belt-like geometries along fault strikes, with vertical distribution controlled by fault-cut stratigraphic intervals, and are dominated by high-angle shear fractures and partly open fractures whose effectiveness rapidly decreases away from faults. Fold-fracture-type FRBs formed during middle-stage fold growth and are concentrated in anticline hinges, high-curvature fold limbs, and local flexural zones. Their fracture development is controlled by fold amplitude, curvature, sand-body thickness, and mechanical-layer thickness, with fracture density increasing in strongly bent positions. Fault-fold-fracture-type FRBs resulted from the superposition of multi-stage faulting and structural bending and consist of faults, associated folds, and multi-set fracture networks. They are characterized by proximity to faults, large fold amplitude, high fracture density, multiple fracture sets, and strong connectivity. This study provides a geological basis for FRB classification, genetic interpretation, and fracture sweet-spot prediction of structural fractured tight sandstone reservoirs in the Xu 4 Member.