A　photonics-assisted　omnidirectional　3D　positioning　radar　for　noncooperative　multi-targets　is　proposed　and　demonstrated.　A　cross-shaped　antenna　array　containing　two　linear　antenna　arrays　(LAAs)　with　symmetrical　structure　is　designed　to　receive　echo　signals.　Through　polarization　multiplexing　modulation,　the　received　signals　from　the　center　antenna　could　provide　overlapped　reference　frequencies.　According　to　specific　symmetry,　de-chirped　frequencies　of　echo　signals　from　each　target　can　be　distinguished.　Two　angle-of-arrivals　(AOAs)　could　be　extracted　to　obtain　the　azimuth　angle　and　elevation　angle　of　multi-targets.　Three-target　proof-of-concept　experiments　are　implemented,　and　the　results　verify　the　capability　of　omnidirectional　3D　positioning　for　multi-targets,　which　supplies　an　alternative　for　the　detection　of　low,　small　and　slow　(LSS)　targets.　©　2023