The common analytical instrument for dioxin analysis/determination is gas chromatograph (GC) coupled with an electron capture detector (ECD), a flame ionization detector (FID), and a mass spectrometer (MS) , etc. Generally, since the concentration levels in environmental samples are pg/g or pg/L, it requires a very high resolution and sensitivity for the analytical system. To solve the problem one way is to increase the amount of a sample, however, which can significantly increase the pretreatment work load. The other way is to increase the injection volume. In this paper, a method for dioxin determination was developed using GC-MS coupled with the large volume injection (LVI). Under the condition of maintaining the same amount of solute, the comparison was studied for the changes of peak areas and peak widths by the injection of different volumes from 1 to 100 microL. The results showed that the peak area and peak width did not have obvious changes, and the separation performance was not affected compared with the traditional split/splitless injection. The detection limits obtained are improved by 1 - 2 orders of magnitude over those using split/splitless injections. Once the operation conditions are optimized, LVI is more flexible in handling samples of wide concentration ranges than the traditional split/splitless inlet approach.