Abstract: Abstract：This work was to the absorbed dose and the distribution of dose field about 125I brachytherapy seed source in body are calculated by used AAPM TG No.43, and measured by used TLD. Both the results of the theoretical calculation and the experimental measurement show that the basically agreeable with the distribution of dose field for seed source，dose of seed source is the exponential decay with the distance, moreover, the decay decreased quickly in 10mm distance range. It shows that the dose of seed source concentrate basically on the near distance range.