This thesis summarizes the recycling of chemical iron sludge, draws a conclusion that scrap iron sludge can be used in the fields of preparation of ironmaking raw material, iron oxide pigment, ferric salt and new material, and put forwards that new prospect of cyclic utilization and application of iron sludge in the productive process of preparing metanilic acid with m-Nitrobenzenesulfonic acid makes iron sludge develop in the direction of high added value from low added value and bring favorable economic benefit and social benefit.