Electric power load modeling system can help people forecast and analysis the development trend of electric power loading. Because the load modeling system is built on the accumulation of a very mass of data and these data need systematical managing, it is pretty necessary to construct database. This paper studies the construction of electric power load modeling system based on actual electric power network of Hunan province, analyzes the all three kinds of data used in this system, and discusses how to build database for electric power load modeling system by use of VB+SQL Server technique.