The invention discloses a method for efficiently preparing lithium carbonate. The method specifically comprises the following steps: 1, performing filtering pretreatment on carbonic acid type salt lake brine, and regulating the pH value to be 3.4-4.8 so as to obtain first liquid; 2, adding magnesium chloride into the first liquid, uniformly mixing and stirring, performing solid-liquid separation,evaporating and concentrating the liquid part, and treating in an electric field so as to prepare second liquid; 3, adding an alkaline solution into the second liquid, uniformly mixing and stirring, and performing solid-liquid separation to obtain third liquid; 4, fully stirring the third liquid, an aqueous dispersant and loofah extract in a hydrothermal synthesis reactor, sealing the reactor, heating the reactor and reacting, and filtering the slurry in the reactor so as to obtain a lithium carbonate filter cake; and 5, washing the lithium carbonate filter cake with deionized water, and drying, thereby obtaining the finished product. According to the method disclosed by the invention, different interfering ions are removed by different steps, and the purity and yield of the obtained lithium carbonate are better than those of the conventional method.