Revers eosmosis,a clean and highly efficient water treatment technique is widely applied to various in dustries.But its in adequate maintenance may easily lead to various problems for RO systems.According to the running experience of 400t/h in the RO system in China Great Wall AluminumCorp.,some problems,such as the SDI control,adjustment of running parameters,and the maintenance and cleaningof the RO system, are discussed and analyzed.