Abstract: The dynamic range of images produced by X-ray image intensifier is always not wide enough. So a dynamic range extending technique of X-ray images was raised. Two X-ray images with different tube voltages were fused through digital wavelet transform to extend the dynamic range of the single one. The experimental results showed that dynamic range could be extended well by the technique. Comparing with the X-ray image whose tube voltage was the median, the fusion image was better in quantitative indicators.