Objective: To observe the effects of radiographic exposure on marginal microleakage for treating dental caries with Filtek Z350 nano resin and FX-Ⅱ reinforced glass ionomer cement. Methods: 40 premolars were randomly divided into four groups with 10 teeth in each group: radiographic exposure group A1 and A2,control group B1 and B2. Cavities were prepared on the buccal side of all the teeth, then the teeth in group A1 and B1 were filled with Filtek Z350 nano resin, and the teeth in group A2 and B2 were filled with FX-II reinforced glass ionomer cement. The teeth in group A1 and A2 were irradiated once a day and 2.0Gy a time, and the total exposure was 70Gy; While the teeth in group B1 and B2 were not irradiated. All the teeth were dyed with 2.0% methylene blue solution after 500 times thermocycling, and the microleakage depth were measured under somatic microscope. Results: Filled with same filling materials, there was no significant difference in microleakage depth between radiographic exposure group and control group (P>0.05). Radiation or not, there was no significant difference in microleakage depth between different filling materials (P>0.05). Conclusions: For patients with head and neck tumor who are prepared for radiotherapy in clinic, Filtek Z350 nano resin and FX-Ⅱ reinforced glass ionomer cement can be used to treat dental caries, they all can obtain fairly stable edge sealing effects.