The effects of P on element segregation, Laves phase dissolution and elemental diffusion in GH706 alloy have been investigated. The results show that P promotes the segregation of Nb and Ti. Phosphorus was enriched in Laves phase, which enhanced the precipitation of blocky Laves phase, while constrained the formation of eutectic Laves phase. Moreover, more needle-like phase was formed around blocky Laves phase in high P-doped alloy. It also demonstrated that P slightly lowered the melting-point of Laves phase. During the homogenization process, P hindered the diffusion of Nb which blocks the diffusion of Nb and dissolution of Laves phase, and complicated the homogenization treatment.