In　power　converter,　the　system　model　has　a　significant　meaning　of　the　design　of　the　controller　and　the　dynamic　characteristics.　In　this　paper,　the　switching　network　average　method　is　used　to　set　up　the　small　signal　model　of　flyback　circuit,　which　is　operating　in　discontinuous　current　mode(DCM).　A　controller　with　single　zero　and　single　pole　is　designed　based　on　the　small　signal　model　which　is　set　up　in　this　paper.　Moreover,　the　analysis　of　system　stability　and　dynamic　response　is　proposed.　Finally,　the　system　is　simulated　and　verified　by　a　flyback　LED　constant　current　drive　circuit　(220AC　input,　0.7A/16W　output).　©　Published　under　licence　by　IOP　Publishing　Ltd.