The invention discloses a simulation computing method and device of a landslide surge disaster. The method comprises the steps of building a three-dimension computing domain model according to the obtained terrain, the water level and the landslide mass shape and the position information; according to a Navier-Stokes partial differential equation set which conducts integral in the thickness and water depth direction of the landslide mass, obtaining the motion of water and the landslide mass and the mutual effect of the water and the landslide mass, and simulating the process that surges are generated, propagated and climbs along a bank according to the change of the water pressure after the landslide mass enters the water; visualizing the landslide motion and the surge propagation rule, conducting numerical forecasting on the surge motion trail and the impact influence area, and evaluating the surge disaster. By means of the simulation computing method and device of the landslide surgedisaster, by conducting numerical forecasting on feature parameters and the influence area of the surge motion, the surge disaster can be evaluated, the method and device have great theoretical significance and high practical value in evaluating the surge disaster and predicting the landslide on the reservoir bank and the secondary disaster of the surges, and also have reference significance in numerical simulation of geological disasters like debris flow and barrier lakes.