The design of huge engineering, such as hydroelectric engineering, is a complex and hard work. Using computer to aid design is the objective which people have being pursuit for. With the technique of Geographic Information System, the methodology of engineering visual computer-aided design and its application are deeply studied in this thesis. The study would be very helpful to promote the reformation of modern engineering design with the tendency to digitalization, visualization and intelligence, and the perspective of its application would be very bright. Summarily, the main contents and achievements of this thesis are listed as following: Firstly, the methodology of GIS-based engineering visual computer-aided design is presented in this thesis in order to enhance the level of computer-aided design, simplify the complex design process and improve the design efficiency. Based on the method, the design modeling and interactive control could be realized conveniently and visually during the design process, and the visual representation of design result could be obtained. Therefore, the efficiency and quality of the design could be largely promoted. Secondly, the artificial neural networks and mixed evolutionary computation are employed into the mathematical simulation of complex geological structure, and with GIS and visualization technique, the method of geological digital 3-D modeling and visualization is presented. So, not only the functions of making geological section and querying spatial information could be achieved, but also the spatial distribution of geological structures and their complex relationship could be described visually. Thereby an interactive and convenient way for engineering geological design could be actualized. Thirdly, the GIS-based three-dimension dynamic visual simulation technique to engineering construction is presented in the thesis. Consequently, the space-time relationship among the complex engineering construction could be visualized, the process of simulation modeling could be simplified, and the simulation information could be obtained and represented visually. Fourthly, this thesis presents a method of visual computer-aided design to concrete dam construction by using three-dimension dynamic simulation. By this means, not only the design modeling process is simplified, but also the complex construction process is visualized. Moreover, it is possible to make analysis andcomparison for the different schemes conveniently. And then a scientific and reasonable decision support can be produced to make the feasible construction planning and the real-time schedule control and management. Fifthly, the method of visual computer-aided design to construction diversion temporary structures is presented. Additionally, the multi-criteria optimization for construction diversion structures based on improved genetic algorithm and the estimation of real-time risk of the cofferdam's retaining flood by using daily streamflow are also studied deeply. And then a CAD system for construction diversion design (CDCAD) is developed. Therefore, a scientific and convenient means to construction diversion design is given. Sixthly, the approach of three-dimensional dynamic visual analysis to the process of construction diversion and river closure is presented basing on the simulation technique, and a corresponding system (CDVAS) is developed. With this study, the complex dynamic process would be described visually, which could provide support to feedback design and facilitate multi-scheme analysis, and a strong analysis tool for the design and decision-making of construction diversion and river closure is achieved.