RESUMEN
OBJECTIVE@#To investigate the advantages of nitric acid digestion method and its differences with the traditional method.@*METHODS@#Ethanol was used to fully fix the testing sample. About 80-100 g of the testing samples were cut into pieces and digested with nitric acid. It was then centrifuged and washed to remove organic components. Smears were prepared and examined under the light microscope.@*RESULTS@#The diatom had been identified with clear striations, counted conveniently and classified easily.@*CONCLUSION@#The improved nitric acid digestion method is not only simple with a higher successful rate of detection, but also can prevent interference from contamination. It can improve the stability of the experimental results, avoid harm to human and environment, and provide higher safety in the course of experiment.