Abstract: Landslide hazard is the most serious type of geological hazards in Lanzhou city. It has the characteristics of large quantity and scale, abruptness, short duration and damaging. in the authors use the support of MapGIS and design and develop the landslide hazard meteorological early-warning system for the disaster prevention and mitigation service in Lanzhou city. On the basis of the collected information, internal and external factors which lead to landslide are quantified in GIS, the authors get the relatively stationary landslide hazard potential risk assessment figure of Lanzhou city. By analyzing the relationship between rainfall and landslide hazard, the authors get the rainfall threshold expression. The system provides four rainfall models and two early-warning models, which achieves the diversification of models. Rainfall is quantified by four rainfall models. Potential probability value of landslide hazard in Lanzhou city is coupled with rainfall probability value, which is based on two early-warning models. Each model of early-warning system provides three, four and five limits of threshold for the final mapping selection. Through MapGIS k9 IMS secondary development platform, the system realizes Web publishing of real-time information of landslide hazards. The system realizes the automatic process from data acquisition to analysis and calculation, finally site released, which provides the basis for decision-making of disaster prevention and mitigation of Lanzhou city.