With the corroded steel strands from prestress concrete beams contaminated with simulated acid rain, the corrosion rate of the steel strands were calculated and the configuration of the pits were surveyed and classified. Then, with 4 samples of 80cm long steel strand were intercepted at the distribution central areas of the pits, the density, length, width and depth of the pits were obtained to explore the distribution characteristics of size of pits on steel strands corroded by simulated acid rain. The results reveal that the configuration of the pits can be classified to ellipsoid, saddal and pyramid. With the corrosion rates increasing, the pits become denser but its relative increase rates declined. The length dose not subject to normal distribution and subjects to lognormal distribution with the depth, and the width merely subjects to lognormal distribution approximately. It is the general distribution characteristic of size of pits that the short and narrow and moderate deep pits are majority on the corroded steel strands. The fractal characteristics were revealed on the distribution of the length and depth, but does not show on the distribution of the width obviously. With the corrosion rates increasing, the configuration of all pits are trend to approach. The length is found at the relative minor values and the width is found at the relative moderate values, however, the depth is found between the relative minor value and moderate value.