The effect of silicon contents (4wt%~8wt%) on microstructure of high-silicon austenitic stainless steel ZeCor was investigated by XRD, TEM and indentation deformation. Results show that increasing Si content leads to the phase constitute change of ZeCor alloy: the microstructure is single-phase austenite (γ phase) in ZeCor-4wt%Si alloy, γ phase with a small quantity of σ-phase in ZeCor-6wt%Si alloy, and as for the ZeCor-8wt%Si alloy, the main precipitations are Cr₃Ni₅Si₂ phase and a bit σ-phases. In addition, the Cr₃Ni₅Si₂ phase has a higher silicon and nickel content than the σ-phase. The Cr₃Ni₅Si₂ phase with a micro-hardness HV as high as 7840 MPa is a typical hard and brittle phase, and the precipitation of such phase can greatly increase the micro-hardness of the γ matrix in the ZeCor-8wt%Si alloy. The strengthening mechanism of γ matrix in ZeCor alloy is as follows: the solid solution strengthening is the main strengthening mechanism in ZeCor-6wt%Si alloy, while the solid solution strengthening of Si and the precipitation strengthening of Cr₃Ni₅Si₂ greatly increase the micro-hardness of the γ matrix in ZeCor-8wt%Si alloy, and the Cr₃Ni₅Si₂ phases have a great effect.