Wet digestion is used as the pre-treatment technology for the electrochemical detection of heavy metals in food, and the complete wet digestion condition of food sample is optimized by electrochemical experiments. The results show that the experimental samples can be digested completely using the Nitric acid-hydrogen peroxide system and is not pre-digested after adding 10 mL nitric acid at 120~140 ℃ and adding 10~15 mL of hydrogen peroxide during the heating process. The correlation coefficient of electrochemical detect is 0.99 for digestion solution of the samples， and the recovery of standard addition is 82%~115%. Wet digestion as a pre-treatment technology of food samples, It can digest sample fully and meet the requirements of electrochemical detection.