Quantitative analysis of the role of factors of the effective utilization coefficient of irrigation water has a significant practical guide sense for the increase of coefficients. Based on the analysis of observed data from 2005 to 2011 in sample irrigation districts of Guangdong Province, the factors were divided into dynamic and static. Among them, eight factors including terrain, channel characteristics, soil texture, engineering, supply and consumption, farming area, water conservancy project investment, and benefit were analyzed for quantifying their influences on effective utilization coefficient of irrigation water. The results showed that the dynamic factors represented by engineering, supply and consumption, farming area, and water conservancy project investment play a decisive role to the rapid increase of effective utilization coefficients of irrigation water and, especially the factors watersaving irrigation area and the completion of investment have the most impact.