The aim of this work was to validate the sample preparation using a microwave digestion for determination of total arsenic in a spiked soil. Graphite fernace atomic absorbtion spectrophotometer (GFAAS) technique was used to determine the total arsenic using palladium nitrate Pd(NO3)3 as a modifier agent. The instrumental detection was performed under the condition steps of drying ashing atomizing and cleaning to be 100 1200 2250 and 2600 C. The external calibration curve was constructed using the automatic program based on the master standard of arsenic with 20 ppb. It was found that linearity range was in the range of 1 to 20 ppb with R2>0.999. Based on microwave digestion condition the sample preparation with and without HF was also compared the total arsenic in the spiked soil with a 10 ppb. The result shoewd that the arsenic content obtained fron the prearation with and without HF did not significantly diferent at the 95% confidence limit. The recovery was 80.3 and 82.3% for the spiked sample with 2.5 and 10 ppb respectively. The relative standard deviation was 2.15% (n=11). The results of this work can also confirmed that the preparation method using microwave digestion provided the more advantages such as rapid a little volume of reagents completely digestion.