Abstract: In situ density and moisture content of asphalt pavement are essential controlling parameters that require accurate measurement for quality control and quality assurance purposes. The ground-penetrating radar (GPR) technique could provide non-destructive, non-contact, and full-coverage estimations of pavement density and moisture content. However, the technical readiness and drawbacks, including prediction models, signal processing algorithms, and testing hardware, remain unclear for agencies and construction practitioners, impeding large-scale implementations. This paper aims to provide a thorough review of the theoretical background and current practices of using GPR for non-destructive measurements of asphalt pavement density and moisture content during construction, thereby allowing for real-time correction of over- or under-compaction on site. The principles and applications of GPR-based density and moisture content prediction models were comprehensively summarized. Their strengths and limitations were discussed. Cutting-edge GPR equipment suitable for such applications was introduced, including their system components, application scenarios, and inherent limitations. Factors affecting prediction accuracy were analyzed. Advanced signal processing algorithms were discussed in the end, along with the in-place calibration procedure for aggregate dielectric constants. The reviewed technique could be a guiding tool for real-time monitoring of asphalt pavement density and moisture content using GPR, offering practical insights for future development and standardized deployment in construction quality management.