Abstract: A method for determining 28 elements of diet samples was developed by using vacuum freeze-drying microwave digestion-ICP-MS in HNO₃-H₂O₂ solution system. Under the optimized conditions, the double internal standard elements Rh and Re were used to compensate for matrix suppression effect and sensitivity drift. 4 kinds of certified reference materials were analyzed by the described method and the measured element values. The analytical results show that the detection limits of the 28 elements are 0.01—0.40 μg/L. The recoveries are 82%—114%. The elements concentrations are accorded with the standard values or the reference values. The relative standard deviations (RSD) are 0.4%—16.9%. The contents of 28 elements in 60 diet samples of people in high lung cancer rate area were determined by this method. The data are useful for studying on the relationship between trace elements and lung cancer and giving some rational diet suggestions.