Abstract: Rock, soil, sediments and other geological samples can be effectively decomposed by acid under high temperature and pressure, and be measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The recoveries of most elements were satisfactory, except for the results of Zr, Hf, REEs, Rb, Th, and U. In this paper, the traditional pressurized acid digestion method has been improved as the sample was extracted by hydrochloric acid instead of nitric acid. 46 elements in the National Standard Materials of rock, soil and sediments can be accurately determined by this improved method. Sample weight was increased from 25 mg to 100m and digestion time was extended from 12 h to 48 h,which effectively resolved the problems including the representation of the samples and inadequate results for Rb, Sr, REEs and other elements dissolved by HNO₃. The results of many experiments showed that the 44 elements measured were consistent with standard values except for As and V elements, according to Cl interference in ICP-MS. Detection limits of the improved method were 0.01-0.85 μg/g, with a precision RSD(n=10) of 0.73%-13.1% and an accuracy RE(n=10)of less than 10%. The improved method is accurate, reliable and suitable for a variety of different types of geological samples.