Cross-regulation　is　one　of　the　critical　challenges　in　single-input　and　multi-output　converters.　In　this　study,　new　design　guidelines　and　an　analytical　model　for　studying　the　cross-regulation　between　the　dual-outputs　of　the　fly-buck　converter　are　proposed.　A　small-signal　AC　model　is　first　established　to　obtain　control　over　the　output　and　to　determine　the　cross-influence　transfer　functions　of　the　system.　Then,　a　load　regulation　coefficient　and　method　for　analysing　the　cross-regulation　while　considering　the　load　magnitude　and　load　change　are　proposed　to　study　the　characteristics　of　the　fly-buck　converter.　Finally,　to　demonstrate　the　rationality　behind　the　influencing　factors　over　cross-regulation　based　on　the　resulting　characteristics,　a　fly-buck　converter　with　double　control　variables　and　lower　cross-regulation　is　designed.　Simulations　and　experimental　prototypes　are　implemented　to　demonstrate　the　effectiveness　of　the　proposed　theoretical　analysis.