Since the discovery of superconductivity at 80 K in single crystals of La3Ni2O7 at pressures above 14.0 GPa [1-5], extensive efforts have been made to understand the properties of the bilayer nickelate system at both ambient and high pressures. CDW, SDW, structural transition, strange metal behavior, orbital dependent correlations, etc., which are profound in copper oxide and iron-based superconductors, are also present in the pressure-dependent phase diagram of La3Ni2O7. They may be related or irrelevant to the superconductivity of nickelates under pressure. Currently, many questions are open. In this talk, I will briefly introduce the discovery of the superconductivity in La3Ni2O7 and discuss the research progress in nickelate superconductors.