CuSn8P alloys, which are used as important materials for the transmission of engineering machinery equipment, operate in environments containing corrosive media. During its service life, it is required to have high corrosion resistance. Thus, research on its corrosion behavior and corrosion mechanism holds significant engineering significance. In this work, the corrosion behavior of CuSn8P alloys with different organizations in a simulated seawater environment (3.5 wt.% NaCl solution) was investigated via electrochemical corrosion tests. The microstructure, polarization curves, impedance spectra and corrosion morphology of the CuSn8P alloy were analysed via OM, XRD, SEM and other characterization methods to explore the corrosion mode and mechanism. The results show that the as-cast CuSn8P alloy (CuSn8P-CS) consists of dendritic crystals composed of an α-phase and (α+δ) eutectic, and the CuSn8P alloy in processing state(CuSn8P-PS) consists of an equiaxed α-phase and deformed twin crystals. The corrosion current density of CuSn8P-PS is low (2.596×10-5 A/cm2), and the corrosion potential is high (-0.943 V), indicating good corrosion resistance. Pitting corrosion mainly occurs in  CuSn8P-PS, whereas uniform corrosion occurs in CuSn8P-CS. The corrosion products are Cu2 O and Cu2 (OH)3 Cl, forming a Cu2 (OH)3 Cl+Cu2 O double-layer protective film, which endows the alloy with excellent corrosion resistance.