According to the measurement errors caused by manual adjustment and the random error caused by surface damage of bullet, 3D data and image processing on the bullet mark are researched. Coordinate transformation measurement data preprocessing can be used, through the wavelet transform to reduce the random error, the treatment of data and images can be obtained, and the 3D data of the bullet mark before and after processing are contrasted. The results show the contrast reliability can be increased by this method, multiple bullets can be compared simultaneously, and the working efficiency is improved.