The fundamental principles of Beidou navigation satellite system (BDS)/global navigation satellite system (GNSS) and interferometric synthetic aperture radar (InSAR) technology were outlined, with a focused review of their theoretical developments since the 21st Ccentury. The latest research advances in their integrated application for deformation monitoring were analyzed in depth. Core issues and potential challenges currently faced by the combined BDS/GNSS and InSAR technology in monitoring engineering deformation and ensuring safety prevention for high-steep slopes were summarized. It is suggested that this integrated approach can achieve centimeter-level accuracy while enabling full-area coverage, significantly enhancing the capability for high-steep slope deformation monitoring. Furthermore, it is pointed out that future efforts should focus on deepening the integration of BDS and domestic SAR satellite data based on an integrated space-air-ground monitoring network, alongside the development of industry-specific large language models tailored for high-steep slope monitoring.