The heat island effect of major cities around the world and the associated environmental and ecological problems have become more and more serious with the global warming and the speedup of urbanization process. In the view of geological and environmental protection, this paper analyzes the causes and characteristics of urban heat island effect and its impact on the geological environment. I In particular, this paper focuses on the variation of soil engineering properties that arise from the effect and corresponding disaster effect. Furthermore, this paper presents four key scientific issues: i.e., soil temperature changes, moisture migration laws in the soil, the variation of soil engineering properties and the geological disaster effect in the urban heat island. The paper also analyzes their detailed research contents. This paper points out the great theoretical and practical significance for understanding urban heat island effect on soil engineering properties, urban geological disaster prevention and reduction, and the urban sustainable development.