The　main　circuit　configuration　of　DC　active　power　filter　used　in　a　special　high　precision,　low　ripple　and　large　power　DC　stable　power　supply　and　its　basic　concept　for　suppression　of　harmonics　are　analyzed,　and　the　control　strategy　of　DC　active　power　filter　with　ripple　voltage　detection　is　presented.　The　advantage　of　this　control　strategy　is　easy　to　meet　the　requirements　of　low　current　ripple　in　DC　stable　power　supply　while　the　precision　of　the　transducer　and　circuit　components　is　not　strictly　requested.　Tests　of　a　practical　industrial　device　with　the　DC　active　power　filter　show　that　its　ripple　achieves　1X10-5.