Abstract: In order to obtain the best image quality for X-ray digital imaging inspection of plate composite, CIVA simulation software was used to calculate the influence of different detection voltages and detection currents on the X-ray digital imaging inspection results of the internal gaps of the plate composite components. The optimized process parameters of the ray source were obtained, i.e. the focus size of 0.8 mm, detection voltage of 100 kV, and detection current of 9 mA. When these process parameters of the ray source were applied to test the samples with prefabricated 0.5 mm gap size, the measurement error of gap size is only 2%, which indicates that the CIVA simulation software can guide the determination of the detection process parameters and ensure the reliability of the detection results.