Abstract: The trace Th and U in 10 kinds of Chinese foods are determined by induced coupled plasma mass spectrometry (ICP MS). The optimum instrument parameters have been selected. Re is used as an internal standard element to compensate for non spectrum interferences arising from matrix elements in the solution and sensitivity drift. Detection limits are 5.7 ng/L for Th and 10.4 ng/L for U (3σ, n =6). The accuracy of this method is corrected using standard sample NIST SRM 1548 as total diet. The analytical results are in good agreement with certified values. On the basis of strict quality control, grain, bean, potato, meat, egg, aquatic product, milk, vegetable, fruit and sugar samples are digested by mixed nitric acid and perchloric acid and determination of U and Th in sample solution by ICP MS directly without separation and enrichment procedure.