Uniaxial tension tests and hole-expansion tests were carried out to determine the influence of silicon on the microstructures, me-chanical properties, and stretch-flangeability of conventional dual-phase steels. Compared to 0.03wt%silicon, the addition of 1.08wt%sili-con induced the formation of finer ferrite grains (6.8μm) and a higher carbon content of martensite (Cm≈0.32wt%). As the silicon level in-creased, the initial strain-hardening rate (n value) and the uniform elongation increased, whereas the yield strength, yield ratio, and stretch-flangeability decreased. The microstructures were observed after hole-expansion tests. The results showed that low carbon content martensite (Cm≈ 0.19wt%) can easily deform in coordination with ferrite. The relationship between the mechanical properties and stretch-flangeability indicated that the steel with large post-uniform elongation has good stretch-flangeability due to a closer plastic incom-patibility of the ferrite and martensite phases, which can effectively delay the production and decohesion of microvoids.