The invention relates to a GIS (
geographic information system)-based distributed-type rice field 
nitrogen runoff loss load estimating method. The method includes: 1), collecting basic information of a studied area, namely collecting daily rainfall, 
evaporation capacity, administrative area, 
land use map and 
soil map of the studied area; 2), investigating basic data of fertilizing and field 
moisture management; 3), generating a related space 
distribution grid map layer; 4), measuring and calculating dynamic changing rules of rice field 
surface water nitrogen concentration under different soil types, namely dynamically monitoring rice field 
surface water under different soil types and different fertilizing levels, and calculating fitting equation parameters of the rice field 
surface water; 5), calculating rice field 
nitrogen runoff loss load including a water quantity balance module, an initial concentration calculating module and a load output module. By the GIS-based distributed-type rice field nitrogen runoff loss load estimating method, temporal and 
spatial change of non-point-source-generated 
pollution discharging coefficient can be reflected, few basic data and parameters are needed, 
model building is easy, and running efficiency is high.