Analysis ofχ phase precipitation in 2205 duplex stainless steel aged at 700 and 750? has been investigated systematically. The experimental results showed thatχ phase forms prior to the precipitation ofσ phase and disappears onceσ phase starts to precipitate. This phenomenon indicates thatσphase nucleated and consumed theχ phase. Theσ phase nucleated mainly at ferrite/austenite interface and grew inwards into the ferrite phase. The morphology ofσ phase reveals a coral-like structure at the temperature of 700? for 120 min followed by quenching in water. The decomposition of ferrite occurs via the following eutectoid reaction:F→σ+γ2. The selected area diffraction pattern of zone axes is[ 1]χ|[ 1]δ, indicating a characteristic orientation relationship betweenχ phase andδ-ferrite.