The fractal characteristics of 2-D projected real electrical tree grown at the tip of needle electrode embedded in polymer insulator were studied. Specimens used in this investigation were reactive additive succinonitrile (SN) added diglycidyl ether of bisphenol A (DGEBA)/4.4''-methylene dianiline (MDA) systems. The treeing tests were carried out in a needle-plane electrode geometry under AC voltage application to simulate the stress concentration. The fractal dimension (D_f) was investigated by scale covering method. The electrical tree and fractal characteristics with self-similarity in time and space domain being independent of observation angle. The D_f at 25℃ increased with increasing tree length, then was saturated to 1.50. At 100℃, however, the D_f of the initial tree was 1.5 and slightly decreased to 1.45 as the tree propagated. As the applied voltage increased, the D_f decreased at 25℃, whereas it increased at 70℃. The fractal characteristics reflected the degree of treeing deterioration, quantitatively.