As the Sr, Nd and Pb isotopic samples are likely to be contaminated during the process of powdering, the method adopted by the Isotopic Laboratory at the University of Hawaii is introduced in detail. The process consists of choice and cut of samples, coarse fracturing, cleaning, picking up and powdering. With this method, the contamination by other materials can be reduced to the minimum, and the advert effects of some alterations and oxides can be eliminated.