The invention discloses a method for preparing 
lithium carbonate by using 
lithium aluminum-containing rock. The method comprises the following steps: S1) the 
lithium aluminum-containing rock and a 
sulfur phosphor mixed acid leaching agent are mixed, a mixture is leached, the mixture is filtered to obtain a lithium-containing 
leachate; S2) 
hydrogen peroxide is added, then the materials are continuously stirred, an 
ammonium hydroxide solution is added for adjusting the pH value, water is added for 
dilution, the material is filtered to obtain a lithium-containing purified solution; S3) the lithium-containing purified solution is subjected to evaporative concentration to form a hot saturated solution, the hot saturated solution is cooled for 
crystallization, and mixed crystals of 
ammonium sulfate and 
ammonium biphosphate can be precipitated to obtain a lithium-containing concentrate; and S4) finally 
magnesium chloride is added, the pH value is adjusted by gradually adding a 
sodium hydroxide solution, the materials are stirred and reacted under normal temperature, 
filtration is carried after the reaction is finished, and the material can be filtered to obtain a 
phosphate-removing filtrate. and S5) the 
phosphate-removing filtrate is heated for concentration, 
solid sodium carbonate is added, after the reaction is finished, 
filtration is carried out while hot, the hot water is used for washing the precipitates, and the precipitates are dried to obtain the 
lithium carbonate. The method employs a chemical 
precipitation method, ammoniacal liquor is taken as a precipitating agent, 
magnesium salt is taken as a 
phosphor precipitating agent, lithium and 
aluminium separation is realized, lithium and 
phosphor separation is realized, and the 
lithium carbonate can be finally prepared.