Data prefeching is used to improve system performance and thuoughput, which ignores the disk energy comsumption. As for this problem，a delaying asynchronism prefeching, clusting disk I/O handle way is proposed based on tradition prefeching to reduce the disk state switching and extend the length of disk idle phases for saving power. We also validate and evaluate this algorithm based on the really running simulator. Our simulations show that compared to stand prefeching with negligible loss performance, our algorithm saves 17% more disk energy.