Mobile robot inspection has significant application value in the power and industrial sectors. This paper identifies several issues in traditional robot inspection systems, including robot navigation, task deployment, and defect/anomaly detection. A unified spatial map architecture called “Meta-space” is proposed based on high-fidelity reconstruction algorithm. This architecture enables modeling features, structure, appearance, and semantics of inspection scenes, along with corresponding implementation methods. By utilizing this map architecture, a digital twin-based mobile robot inspection system is developed, and reference methods based on this architecture to address the key issues are proposed, including robot localization and navigation, inspection task virtual deployment, and scene-based fine-tuning of the detection model. Finally, experimental results validated the effectiveness of the unified spatial map architecture and the associated methodologies.