An apparatus for preparing graphene by means of laser irradiation in liquid, comprising a laser generating system, and further comprising a computer control system, a cleaning and drying system, and a workpiece auxiliary system. The light spot diameter of the laser emitted from a pulse laser unit (26) is increased by means of a beam expander (24), and the laser is reflected and split by a beam splitter to form two laser beams; a first laser beam (19) shocks the right vertical plane of a graphite solid target (18) by means of a focusing lens, and a second laser beam (17) shocks the left vertical plane of the graphite solid target (18) by means of the focusing lens, so as to grow graphene on a copper foil (5) substrate.