We numerically demonstrate the phase regeneration of eight-phase-shift keying (8PSK) in an organic-Ge hybrid waveguide with 10 μm length. Through filling graphene oxide with a high Kerr coefficient and engineering of waveguide dimensions, an ultrahigh nonlinear coefficient with 5.86x106 W-1 m-1 is attained at 1550 nm. The phase regeneration of 8PSK signal is achieved by using phase-sensitive amplification of the dual-conjugated-pump degenerate four-wave mixing scheme. The error-vector magnitude (EVM), optical signal-to-noise ratio, as well as constellation diagrams of 8PSK signal are also used to evaluate the phase regeneration capacity quantitatively. A reduction of EVM from 39.25% to 1.34% for 8PSK signal is found. The results show great phase regeneration and noise-squeezing ability, which indicate that such a phase-sensitive amplifier of a waveguide can find critical promising applications in all-optical signal processing. ©2022 Optica Publishing Group.