With the development of the national economy and society, the scale of highway construction and operation in China has been expanding continuously. Currently, the mileage of all levels of highways and expressways in China has surpassed that of the United States, ranking first in the world. This book takes road engineering geological investigation as the research object. Based on the analysis of its significance, it conducts in-depth exploration of road engineering geological investigation and construction from different perspectives, such as road alignment engineering geological investigation, construction site investigation for road structures, and engineering geological investigation for sections with complex geological conditions. This book holds high reference value for both road engineering technicians and researchers in related fields.