Taiwan is on the pacific ring of fire with high probability of compound-disasters that is one of the top ten of high natural disasters threatened areas in the world. It's very difficult to predict ”when” the earthquake will occur, but somehow having the fastest way to get the rescue resources to targeted disaster-striking areas is the key for saving more lives and properties in order to minimize the casualty within the golden 72 hours' time restriction. This study aims at finding the fastest routes after impact of major earthquake with a model developed by us, called the model of optimal routes for rescue after earthquake, that concerns the dynamic initial status of roads conditions to shape the Dijkstra algorithm for the purpose of optimizing the routes under instant image/data of the usable transportation network. The output of this model may assist the decision-maker to select the fastest route for getting the rescue team out to the targeted urgent areas for reducing the potential casualties caused by earthquake.