Due to economic development, population growth and climate change, water resources become shortage. Therefore, desalination technology has become a key technology developed by many countries in recent years. Capacitive Deionization (CDI) is a technique for removing ions from water by electrosorption. There are several advantages of CDI system, including no secondary pollution, easy to install and energy efficiency. The electrode material is one of the most important factors to affect the performance of CDI. Therefore, in this study we focus on developing nano Fe/graphene composites to remove salt and heavy metals from water. The electrode material used in this study is holey graphene. The holey graphene is graphene treated with mixed strong acid (HNO3:H2SO4=2:1). Due to slightly hydrophobic property of graphene, which is not desirable for water treatment process, we employ the mixed strong acid to improve the hydrophilicity of graphene. In this study, we want to improve the surface characteristics and electrochemical properties of porous graphene. With addition of nano iron, microwave synthesis or hydrothermal synthesis is used to modify holey graphene. Both methods can increase the specific surface area of the electrode. These two Fe/HrGO composites were applied to the CDI system for electrosorption studies of NaCl solution. The Fe/HrGO composite synthesized by hydrothermal synthesis has better CDI performance than that of microwave synthesis, which has higher electrosorption capacity of 2.86 mg NaCl/g electrode. While the microwave synthesized Fe/HrGO composite can only electrosorb 2.29 mg NaCl/g electrode. Therefore, it is concluded that hydrothermally synthesized Fe/HrGO composites are more suitable for CDI technology. Hydrothermally synthesized Fe/HrGO composites were applied to CDI system for removal of heavy metal (Pb or Cu). In the case of removal Pb, the electrosorption capacity is 4.2 mg PbCl2/g electrode. In the case of removal Cu, the electrosorption capacity is 3.88 mg CuCl2/g electrode.