As the intensity of underground-space development in residential projects continues to increase, underground garages should not be regarded merely as facilities for meeting parking quotas or reducing the average area per stall. They are integrated spaces involving regulatory compliance, construction accuracy, acceptance procedures, delivery communication, and subsequent operation and maintenance. Whether a parking stall can be accepted as effective depends on the coordinated verification of the design vehicle, net stall dimensions, clearances from walls, columns and other structures, aisle and turning conditions, door opening areas, maintenance space for equipment, fire-evacuation requirements, and civil air-defence facilities. Taking completion acceptance and practical usability as the main evaluation criteria, this paper reviews typical risks in parking-stall dimensional control with reference to DG/TJ 08-7-2021 and studies on underground-garage optimization, BIM-based coordination, and construction deviation management. The study argues that underground-garage optimization should connect quota calculation, screening of risk-prone stalls, coordination among column grids, parking stalls and aisles, model-based checking, on-site measurement, and acceptance documentation. A closed-loop mechanism extending from design development to project delivery can reduce stall deduction, rework, and disputes. By reserving reasonable tolerances during schematic and construction drawing stages, continuously checking finished dimensions during construction, and establishing a one-stall one-record checklist before acceptance, projects can better balance cost efficiency, code compliance, and public trust.