Foundation models have become a focus in radar remote sensing intelligent interpretation due to their provision of universal and generalizable solutions. Significant progress has been achieved in both theoretical and applied aspects of radar remote sensing foundation models, making it imperative to systematically summarize current research advancements. In order to further advance the research on radar remote sensing foundation models, the concept, key technologies, and evaluation methods of foundation models was expounded. Besides, current research progress and application performance are reviewed, with representative approaches and typical instances summarized. In conclusion, discussions and future directions are highlighted from four perspectives: model architecture design, interpretability research, lightweight methods, and security assessment.