Focused ion beam analysis method

The invention provides a focused ion beam analysis method, and the method comprises the steps: 1, selecting a to-be-analyzed sample; 2, carrying out the etching of the to-be-analyzed sample through employing an ion beam, so as to obtain a cut cross section; 3, observing whether charge deposition happens or not through an electronic beam: obtaining an electronic beam image when charge deposition does not happen, or else, obtaining the electronic beam image again after an organic source layer is formed on a side surface of the cut cross section; 4, judging whether the obtained electronic beam image displays the target cross section or not: repeatedly carrying out the steps 2-4 till a target cross section is obtained when the electronic beam image displays a non-target cross section, or exporting the obtained electronic beam image when the electronic beam image displays the target cross section, and carrying out failure analysis. The method can prevent an effect of charge deposition from affecting the results of failure analysis.