In order to study water content spatial distribution law of unsaturated tailing sand when seepage arrives steady state and to provide more accurate basic materials for the safety evaluation of tailing dams, this article simplified the equation and solution of the Richards Equation of unsaturated seepage and obtained the spatial distribution of water content using analytical method, and the formula is in the form of infinite series. Then the two-dimensional tailing sand unsaturated seepage experiment was carried out using the instrument designed by the authors, and the water content distribution law of unsaturated tailing sand both in horizontal and vertical directions was obtained. The results showed that water content distribution in both directions matched a exponential function approximately. The unknown parameters which conducted during processing of solving equation were calculated by combining the chaotic particle swarm optimization (CPSO) and the experiment data, and water contents of measurement locations were calculated by the obtained model. By comparison, it is concluded that theoretical values obtained from calculation formula and measured values obtained from the experiment agreed well.