Abstract: Star formation history (SFH) is important in a galaxy’s formation and evolution. It affects the shape, mass, metallicity, color, and many other properties of a galaxy. And it also encodes the physics which drives the galaxy evolution. Retrieving the SFH of galaxies is always a critical issue in the research of galaxy formation. This is a tough task due to the complexities and uncertainties in the formation of galaxy. Benefitted by the arisen of hydro-dynamic cosmological simulation, we can investigate the simulated galaxies without strong prior assumptions on SFH. This provides researchers a powerful tool for investigation on SFH. I would like to show my recent works investigating the SFH in simulations, which may bring light to task of recovering the SFH of observed galaxies.