The sodium dodecyl sulfate is purified by means of recrystallization from water solution after treating it with aether. Its mass fraction increases from 88. 6% to 99. 3% after purification. Its temperature of the extrapolated onset is 190℃ with differential scanning calorimetry(DSC), its critical micelle concentration is 8. 50×10-3mol·L-1at temperature of 40℃ after purification