Abstract: Column leaching seepage processes were detected in a non-contact and non-destructive way by magnetic resonance imaging. Column leaching images were obtained when the flow was stationary and running. Mesoscopic seepage velocity field distribution characteristics and velocity field evolution rules inside pores were studied by analyzing the velocity value distribution, flow velocity distribution uniformity, and relationship between evenness index and spray intensity. The research shows that the velocity distribution has obvious inhomogeneity, and the flow velocity value is not in accordance with the pore size strictly. The flow velocity distribution is similar for different spray intensities. There is a positive correlation between the maximum velocity and spray intensity. A spray intensity threshold can he obtained by analyzing the relationship between velocity field uniformity and spray intensity. The value of 0.7 L·cm^-2 h^-1 is the intensity threshold of the designated graded distribution. Field applications of dynamic spray intensity can obviously improve the permeability of dumps and the leaching rate of copper.