An experimental investigation has been performed to analyze influence of swarming pulsive micro discharge (SPMD) on tree degradation process. The discharge magnitude and luminous image at several phase angle areas of applied voltage were measured using an original measurement system. The luminous image was digitized to the luminous quantity with a computer after experiment. Phase characteristic of the discharge magnitude and luminous quantity in the case of the void discharge passed through SPMD and did not pass through SPMD separately. The result shows deference of luminous quantity at the early stage of tree growth. The tree growth rate was measured and the quantitative evaluation of fractal dimension of the complexity of the tree channels was determined. Consequently, the tree growth rates of the sample passed through SPMD were slower than those of non SPMD and the densities of tree channels of the sample passed through SPMD was higher.