The influence of αs precipitates on electrochemical behavior and mechanical degradation of Ti-1300 alloy in artificial seawater have been studied. The results show that corrosion resistance and mechanical degradation have been significantly affected by the formation of acicular αs precipitates. The precipitated αs phase with an acicular shape around 40–60 nm in width are uniformly distributed inside β grain. Many αs precipitates are intersected each other and keep a well-defined Burgers orientation relationship with β matrix, which restricts the growth of other αs phases due to pinning effect. Within the electrolyte, the αs phases can form “microgalvanic cells” with their adjacent intergranular β phases, which dramatically deteriorate its corrosion resistance. The mechanical properties of the alloy are also degraded with the increase of immersion time due to the pitting reaction. The precipitated microstructure exhibits an inferior mechanical degradation behavior, and this is mainly because a lot of corrosion cavities are nucleate d and propagated at the interface between αs precipitates and prior β grains.