With the rapid development of cities, more and more new roads are built in various civil engineering projects. Subgrade construction is the core of road engineering system. Only by comprehensively ensuring the quality of road subgrade can the road performance be effectively improve and the development of urban construction be ensured. The quality of subgrade determines the traffic capacity of urban roads and plays a decisive role in the safety and stability of traffic. This article mainly analyzes the problems of road subgrade construction in civil engineering, and comprehensively puts forward countermeasures, so as to effectively improve the subgrade construction quality and ensure the smooth operation of roads.