Landslide and flash flood hazards are two most dangerous and implicit hazards in any mountainous region. The model for early warning system of landslide and flash flood hazards is established with the concept of geomorphology and basin hydrology and that the hazards will occur at place with both high implicit potential and high rainfall. In the model, different parameters of each basin are asseseed based on the specialist and semi quantitative methods (Thomas Saaty - Analytic Hierarchy Process - AHP) to establish the implicit hazard map. The software is programmed based on the ArcGIS Engine technology, a GIS product of the ESRI. With the GIS spatial analysis tool, forecasted rainfall at the gauging stations will be quickly interpolated to produce a rainfall continuous layer for whole region and then ovelayed with the other implicit potential hazard layers to create an early hazard warning map. The software has been applied for processing and early warning landslide, flash flood hazards in Rac Kan province, Vietnam for purpose of reducing lost due to these hazards.