Abstract: As an important technological measure, comprehensive prediction in geology can solve many engineering geological problems and reduce the risk of construction in tunneling. But present comprehensive prediction is simply focused on quantity. In order to make comprehensive prediction more effective,a method to identify common adverse geological body is generalized by geo-analysis. Geological defect that may exist in front of face is preliminary determined by this method. Based on the principles of Analytic Hierarchy Process(AHP),factors that effect prediction measures are quantified, and the weight is given to each of them. Then two levels comprehensive appraisal index system are established. All of them is to research the suitability of different prediction methods in a particular engineering geological condition, and to optimize the best ones. The main results are as fallows. Prediction methods are optimized by geo-analysis method and AHP, which are used for qualitative and quantitative respectively. Arbitrary of choosing geophysical exploration measures is eliminated in the comprehensive prediction. The comprehensive forecast technical system is established. Aiming at the F2 Fault of Zijinshan Tunnel, a karst river is predicted successfully at ZK221+960 by using this system. It's verified that the AHP based comprehensive prediction is practicality and feasibility.