The newly discovered Ruddlesden-Popper (RP)-type bilayer lanthanum nickel oxide La₃Ni₂O₇ has emerged as a pivotal candidate in high-temperature superconductivity research, following copper-based and iron-based superconductors. Its superconducting transition temperature reaching 80 K under high pressure has sparked intense interest, yet the correlated electronic properties under ambient pressure—an essential foundation for elucidating the superconducting mechanism—remain insuffciently understood. To address this gap, we systematically investigate the electronic structure and correlation effects of ambientpressure La₃Ni₂O₇ using a combined theoretical approach.