With the development of multiple-collector inductively coupled plasma mass spectrometry(MC-ICP-MS),non-traditional stable isotope system has received increasing interest.Meanwhile,cadmium(Cd) isotope is becoming a research hotspot in recent years due to its unique physicochemical properties and isotopic fractionation characteristics.In addition,Cd isotope has been widely used in the fields of marine chemistry,biochemistry and cosmic chemistry.Sample digestion is a vital step in the process of isotope analysis,and the quality of digestion method directly determines the accuracy of Cd isotope data.In the previous studies,the Cd isotope data obtained by different digestion methods had been investigated for some geological and environmental samples,but few reports had been focusing on the Cd isotope composition of biological samples,e-g.rice flour reference materials.Therefore,the advantages and disadvantages of different digestion methods as well as the effects of sample digestion methods on the Cd isotopic composition of plant samples(rice，reference materials and real rice samples) were further compared.Firstly,dry ashing,acid extraction,microwave digestion and high temperature digestion bombs method were used to digest seven stream sediment(GSD) reference materials,and the effects of sample digestion methods on the high precision Cd isotope detection were evaluated.After that,both microwave acid digestion and high temperature digestion bombs method were used to digest the two rice(GBW) reference materials and six real rice samples.Results showed that the Cd isotope results of stream sediment reference materials obtained by the high temperature digestion bombs were in good agreement with the reported values.However,in the case of dry ashing or acid extraction method,the recoveries for Cd in the stream sediment reference materials were a little too low(it could be as low as 72.8%) due to element loss or incomplete digestion,and the Cd isotope test results would significantly deviate from the true value(maximum deviation of the isotope value Δ114/110Cd reached to 0.24‰).It is worth noting that microwave digestion could achieve a recovery for Cd within 96.6%-98.8%,and the isotope results are in line with the values obtained by high temperature digestion bombs method within the analytical uncertainty(Δ114/110Cd ≤±0.04‰),which indicated that the microwave digestion method could be used to obtain accurate and reliable Cd isotope data.In the follow-up digestion of two rice reference materials and six real rice samples,the Cd isotope compositions obtained were the same as those of the above stream sediment reference materials(Δ114/110Cd≤±0.04‰),further verifying the reliability of microwave acid digestion.All the results demonstrated that microwave digestion was a reliable digestion method for Cd isotope analysis on samples of different matrix types.