Four thousand years ago, ancestors of China had used the spreading measure to mitigate flood damages in the Yellow river. Later, this measure formed an effective system in flood defense together with levee projects. Nowadays, many reservoirs have been built for flood control. However, it is difficult to build reservoirs in the middle and downstream of main rivers in China. The utilization of spreading and detention areas (SDA) are an effective way to mitigate extraordinary floods, but this is accompanied with the severe social problems. For the tradeoff of SDA is difficult to estimate, this measure is still in argue. This measure has been practiced for many years and still be used in China. In recent years, with the advance of flood forecasting and reservoir operation, SDA got effective. This study focus on the SDA in 4 main rivers of China, a comprehensive study is made concerning with the historical, the geographic, the climatic and the social conditions. Major problems of SDA are discussed.