Abstract:The digestion methods in determination of heavy metal were the key step in the analysis process， which were directly related to the precision and reproducibility. The influencing factors of dry-ashing digestion， wet digesting， high-pressure seal digestion and microwave digestion methods were summarized in this paper. The conclusions were as follows： the detection results were affected by the temperature， time， reagents， digest－ ed vessels and the composition of sample. All four methods could be used in cadmium determination， but the high-pressure seal and microwave digestion methods were better. The determination of arsenic should adopt wet or microwave digestion. The open-system digestion was more suitable for determination of cadmium in marine organism samples. Two different methods unit could be better than one method alone.