The subgrade is the main load-bearing structure of highways. With the transition of China′s highway construction from high-speed development to high-quality development, digital construction technology, intelligent construction, and information management have become the core technical means in subgrade engineering. This paper summarizes the research status of key technologies of construction and maintenance for intelligent highway subgrades, mainly analyzing building information modeling (BIM) technology, intelligent compaction technology for subgrades, subgrade health monitoring and assessment technology, and intelligent grouting reinforcement technology for subgrades. The current problems are as follows: the application of BIM technology in the field of subgrade engineering is still in its infancy, lacking reasonable construction quality quantification indicators and cost estimation methods. The theoretical research on intelligent compaction technology is weak, and there is limited research on quality uniformity evaluation. Existing measurement methods for subgrade monitoring and assessment technology are susceptible to interference from other factors and require significant human intervention. In addition, there is no unified quality evaluation index for grouting reinforcement technology, mostly relying on engineering experience and theoretical analysis for evaluation. Therefore, it is necessary to conduct intelligent theoretical and applied research on various key technologies to address the proposed problems and provide guidance for the intelligent construction and maintenance of subgrade engineering in the future.