The invention discloses a method for measuring the 
lanthanum content in a 
lanthanum-iron 
alloy. The method comprises the following steps: dissolving a 
lanthanum-iron 
alloy by 
nitric acid; diluting the solution by water, boiling the diluted solution; then adding hot 
oxalic acid, dropwise adding 5 drops of 
cresol red indicator at the same time, adjusting the pH value by 
ammonia liquor until the color turns from red to yellow, heating the solution to a temperature of 100 DEG C, maintaining the temperature for 10 minutes; allowing the solution to stand still for two hours, filtering the solution by a quantitative 
filter paper, fully washing the precipitate by a mixed water solution of 
oxalic acid and 
ammonium oxalate, transferring the precipitate to a 
filter paper, washing the precipitate by a 
mixed solution of 
oxalic acid and 
ammonium oxalate, placing the precipitate into a 
ceramic crucible, burning the precipitate into ashes; finally burning the ashes in a 
muffle furnace for 30 to 40 minutes, cooling, and weighing. The lanthanum content can be calculated according to a formula: WLa2O3=m1*100% / m, wherein the m1 represents the 
mass of 
rare earth oxides, the measurement unit of m1 is g, m represents the 
mass of a sample, and the measurement unit is g. The 
cresol red indicator is a 
ethanol solution of 
cresol red. The provided method has the advantages of 
short course, low cost, rapidness, efficiency, accuracy, and good stability, and can be easily mastered.