In　order　to　optimize　the　Spurious　Free　Dynamic　Range　(SFDR)　of　microwave　photonic　frequency　down-conversion,　a　microwave　photonic　down-conversion　method　based　on　intensity　and　phase　cascaded　modulation　was　proposed　and　verified　by　using　a　Mach-Zehnder　modulator　(MZM)　with　feedback　control　module　and　a　phase　modulator　(PM).　The　principle　of　frequency　down-conversion　and　influence　of　power　of　local　oscillator　on　system　performance　were　derived　theoretically　and　analyzed　in　simulation.　The　MZM-PM　cascade　microwave　photonic　down-conversion　system　was　built,　in　which　a　self-developed　DC　bias　feedback　module　was　applied　to　enable　the　MZM　at　a　stable　operating　state.　Then　the　performance　of　system　was　tested　experimentally.　The　results　demonstrate　that　the　gain　and　SFDR　are　-6.65　dB　and　108.62　dB/Hz2/3　respectively,　which　have　been　improved　3.56　dB　and　19.87　dB　respectively　compared　with　the　conventional　MZM-MZM　cascade　down-conversion　system.　In　addition,　microwave　photonic　down-conversion　method　based　on　intensity　and　phase　cascaded　modulation　only　requires　a　single　DC　bias　voltage,　and　the　stability　of　operating　state　can　be　controlled　by　the　feedback　module.　The　system　can　offer　microwave　photonic　frequency　down-conversion　in　high　dynamic　range　with　a　simple　structure　and　stable　performance.　©　2017,　Science　Press.　All　right　reserved.