Abstract: This article establishes an analytical method for the metal cotents of calcium, magnesium and iron by inductively coupled plasma emission spectrometry after burning and acidifying samples in boilers and heat exchangers. The sample pretreatment conditions were discussed. Using hydrochloric acid, nitric acid and hydrofluoric acid as acidic media, The recovery rates of calcium,magnesium, and iron in this method meet the requirements of analytical analysis, with a relative standard deviation of no more than 3.5%. It can be used for the determination of calcium, magnesium,and iron metal content in scale samples.