The invention discloses a novel technology for preparing apigenin from naringin by a one-step method. The technology comprises the following steps: all-in-a-pot reaction; concentrate preparation; coarse product preparation; fine product preparation; drying, smashing, detecting, mixing and packaging. A low-cost solvent replaces the conventional solvent while the reaction is not affected; at the preset, a proper solvent is found out; the consumption of a dehydrogenation reagent is greatly reduced during the reaction; in the reaction process, an automatic temperature controller is mounted on a reaction kettle, so that rise or fall of the temperature is realized by manual operation, and the production efficiency is greatly improved; judgment on the reaction end point is controlled through high performance liquid phase, so that the reaction precision is greatly improved; the reaction conditions are mild, the reaction time is short, the yield and purity are higher, environment pollution is prevented, and the production cost is greatly reduced.