Abstract: The tunnel blasting fragment degree is an important factor to evaluate the blasting quality.However，it is difficult to accurately obtain the tunnel blasting fragment by conventional image processing methods because photos are taken in unfavorable environments such as low light intensity，uneven illumination of single light source and large smoke and dust after blasting.Based on ACE and CLAHE algorithm，a new image analysis method for tunnel blasting fragments was proposed.Combined with image block cutting，the interference of low light intensity，uneven illumination and blasting smoke and dust on image illumination and contrast was eliminated.Through bilateral filtering，binarization algorithm，image opening operation，watershed algorithm and other image processing methods，the segmentation image of tunnel blasting fragments can be obtained，and the segmentation of tunnel blasting rock block can be completed.Through the image analysis of a field example，it is verified that this method can better distinguish rock targets and identify the fragmentation of tunnel blasting.The relevant experience can be used as a reference for similar tunnel blasting operations.