The　emerging　360-degree　video　has　a　good　practical　prospect　in　video　broadcasting　due　to　its　more　immersive　experience　than　traditional　videos.　To　maintain　a　high　fidelity　with　panoramic　vision,　360-degree　video　adopts　a　significantly　increased　resolution　than　planar　videos,　which　also　inevitably　leads　to　higher　encoding　complexity.　In　this　paper,　we　propose　a　flexible　complexity　optimization　method　for　360-degree　video　coding,　in　which　the　encoder　is　capable　of　adapting　to　different　complexity　constraints　in　diversified　broadcasting　scenarios.　In　particular,　the　proposed　method　is　realized　with　a　latitude-based　computation　complexity　allocation.　Firstly,　it　investigates　the　Coding　Unit　(CU)　partition　variation　along　the　latitude　(i.e.,　vertical　axis)　and　divides　each　video　frame　into　Largest　CU　(LCU)-based　latitude　regions.　Then,　it　formulates　the　complexity　allocation　problem　from　the　global　complexity　target　to　all　latitude　regions,　by　considering　the　intraframe　dependencies　and　Rate-Distortion　(RD)　models.　Finally,　it　calculates　the　solution　to　this　complexity　allocation　problem　and　further　employs　it　in　360-degree　video　coding.　Comprehensive　experiments　on　the　standard　dataset　reveal　the　superiority　of　our　method,　which　achieves　a　flexible　computational　time　reduction　from　14.53%　to　68.36%　whilst　maintaining　a　high　visual　quality　of　compressed　videos.