In this paper, two kinds of methods, i.e., H2SO4-HNO3-HF and HNO3-HF-HClO4, regulated in the National Standard GB/T17137-1997 and GB/T17141-1997, were used to digest soil samples, and then HNO3-HF-HClO4 was selected and improved to determine the total concentration of chromium by using flame atomic absorption spectrometry. The results showed obvious differences in the measured results between the three kinds of pretreatment methods, among of which, the improved HNO3-HF-HClO4 method was best, it digests fast (3 - 4 h) and fully, reduces the test time greatly; it is of high sensitivity (the lowest detection limit was 0.04 mg/L), high accuracy (the relative error was 1.3% - 5.0% ), high the recovery of standard addition (94.6% - 108.7%) and good precision (the relative standard deviation was less than 5.7%), thus it is worth being applied to the detection of agricultural environmental samples of soil quality.