Abstract: To aim at the evaluation and prediction of the stability of large scale rock slope or underground engineering in the mountainous area, the frame of a Synthetic Geology Information System (SGIS) are proposed in this paper. It is suggested to setup a SGIS for the large geological engineering. Therefore, the whole state of the engineering can be mastered all the time and better decision can be made more quickly in designing and constructing to meet the needs of the rapid development of modern engineering construction of China. A specialized edition of SGIS is developed by the authors. An example of the application of this SGIS in the shiplock slope engineering of a large hydropower station is given.