As　society　evolves,　individuals　increasingly　cooperate　with　both　in-group　members　and　out-group　strangers,　despite　risks　such　as　betrayal.　Social　identity　plays　a　crucial　role　in　motivating　this　cooperation,　significantly　shaping　cooperative　behavior.　This　study　explores　how　social　identity　complexity-arising　from　the　overlapping　of　multiple　social　identities-affects　intergroup　cooperation.　Using　the　Intergroup　Parochial　and　Universal　Cooperation　(IPUC)　game,　we　examined　universal　cooperation,　weak　parochial　cooperation,　and　strong　parochial　cooperation　under　different　payoff　structures-the　equal　outcomes　game　(EOG)　and　the　collective　incentives　game　(CIG)-and　framing　conditions　(individual　and　group　frames).　The　findings　reveal　that　social　identity　complexity　is　positively　related　to　universal　cooperation　and　negatively　related　to　strong　parochial　cooperation.　Individuals　with　high　social　identity　complexity　demonstrated　higher　levels　of　universal　cooperation　and　lower　levels　of　strong　parochial　cooperation,　particularly　within　the　CIG　compared　to　the　EOG.　Additionally,　individuals　with　high　social　complexity　showed　greater　universal　cooperation　and　less　strong　parochial　cooperation　in　the　individual　frame　compared　to　the　group　frame,　while　those　with　low　social　identity　complexity　exhibited　more　weak　parochial　cooperation　in　the　individual　frame.　These　findings　suggest　that　higher　social　identity　complexity　fosters　intergroup　cooperation,　with　different　payoff　structures　and　framing　conditions　significantly　influencing　cooperative　behavior.