Abstract: The decision making system of Yellow River Primary Affair Bureau based on “Internet＋Flood Prevention” adopts B／S structure，the server side provides data and map information to the client by using Web server，database server，Map InfoXtreme for Windows，the client uses the browser.This paper discusses the design idea of system and the key technology of flood control project database establishment and the systems construction，and analyzes the functions of the system，such as data and graphics switching of flood control project，flood control project inquire，dangerous case forecast，flood control material management，emergency supplies calculation，etc.