Control　systems　are　widely　used　in　daily　life　and　support　various　important　infrastructure,　such　as　power,　hydraulics,　petrochemicals,　transport,　telecom,　etc.　Once　the　control　system　is　attacked,　the　consequence　would　be　unthinkable.　The　DES　(Data　Encryption　Standard)　encryption　algorithm　is　open,　and　it　has　the　merit　of　large　encryption　strength　and　fast　computational　speed.　This　paper　describes　the　DES　algorithm,　the　hardware　and　software　design　of　the　DES　hardware　encryption　system　based　on　the　DES　encryption　algorithm　and　FPGA　(Field　Programmable　Gate　Array).　The　hardware　design　includes　the　design　program　of　the　DES　hardware　encryption　system,　the　design　of　S-box　and　the　design　of　circuit　architecture.　The　software　design　is　mainly　to　write　a　s-function　of　the　DES　hardware　interface.　An　experiment　of　a　networked　DC　motor　speed　control　based　on　DES　is　described,　and　this　networked　control　system　has　the　function　of　hardware　encryption.　©2009　IEEE.