Galaxy formation is one of the major challenges in astrophysics. Supernovae (SNe) feedback plays a critical role in galaxy formation, but how it works remains unclear. Galactic outflows driven by SNe remove mass and metals from galaxies, and may prevent cosmic inflows, thus regulating galaxy formation. In this talk, I will introduce our high-resolution, small-box numerical simulations on how SNe drive outflows from a multiphase interstellar medium. I will talk about the amount of mass/energy/metals that are being carried in the outflows, and its implications for galaxy formation. I will also discuss the comparison of OVI 1032/1038A line emission/absorption in simulations to the observations.