A　novel　photonic-assisted　multifunctional　radar　system　was　proposed　and　experimentally　investigated.　This　system　can　simultaneously　achieve　frequency-doubled　linear　frequency　modulation　(LFM)　signal　generation,　de-chirp　reception,　self-interference　cancellation,　and　frequency　measurement　in　an　integrated　transmit-receive　radar.　First,　a　high-frequency　and　broadband　LO　signal　was　obtained　with　photonic　frequency　doubling,　which　improved　the　center　frequency　and　bandwidth　of　the　radar　detection　system.　Then,　photonic-assisted　interference　cancellation　was　used　to　reduce　the　impact　of　interference　signals　in　radar　de-chirp　reception.　Finally,　the　microwave　frequency　measurement　was　achieved　by　establishing　a　mapping　relationship　between　the　envelope　response　time　of　the　intermediate　frequency　(IF)　electrical　filter　and　the　microwave　frequency　to　be　tested.　Both　theoretical　and　experimental　investigations　were　performed.　The　results　showed　that　an　LFM　signal　with　a　frequency　range　of　12-18　GHz　was　obtained　with　photonic　frequency　doubling.　Photonic-assisted　self-interference　cancellation　reduced　the　impact　of　interference　signals　in　radar　de-chirp　reception　by　more　than　12.1　dB　for　an　LFM　signal　bandwidth　of　6　GHz.　In　the　frequency　measurement　module,　the　difference　between　the　frequency　to　be　tested,　generated　by　the　external　signal　source,　and　that　calculated　in　the　experiment　is　the　measurement　error,　and　a　measurement　resolution　better　than　14　MHz　was　achieved　in　the　range　of　12.14　GHz-18.14　GHz.　The　proposed　system　is　suitable　for　miniaturized　multifunctional　radar　signal　processing　systems　with　continuous　operation　of　transmitting　and　receiving　antennas　in　unmanned　aerial　vehicles　(UAVs),　automotive　radar,　relatively　close　spatial　locations,　and　so　on.　In　addition,　it　can　simplify　the　system　structure　and　reduce　space　occupation.