The invention provides a technology and method for preparing solution used for preparing graphene in a liquid phase, comprising the following six steps of: firstly, directly mixing water and alcohol in predetermined proportion, thus the solution used for preparing graphene in the liquid phase can be obtained; secondly, dispersing graphite powder into the solution, thus graphite dispersion is obtained; thirdly, treating by adopting ultrasonic cavitation or jet flow cavitation; fourthly, standing the treated solution, and taking the solution at the upper layer; fifthly, carrying out high-speed centrifugal separation on the solution at the upper layer; and sixthly, collecting supernate at the upper layer after the high-speed centrifugal separation is carried out, thus stable graphene dispersion is obtained. By adopting the solution directly mixed by the water and the alcohol in the invention, the graphene can be prepared in non-toxic pollution-free green solvent with low boiling point, equipment investment is less, raw materials are available, production safety is high, operation is simple and convenient, environmental protection can be realized, yield is considerable, reproducibility is good, and the technology and method provided by the invention are applicable to laboratory study and are also applicable to large-scale industrial production.