The output of a high sulfur gas storage in complex mediums (e.g.cranny or cave type) is the superimposed output from each single well The capacity of a gas well of high sulfur content can be synthetically affected by the seepage condition that determined by the medium complexity degree of storage floor and other aspects, the sediment of sulfur and the producing task.Hence, the output is of complex non-linear characteristic which it very difficult for us to make the prediction.In this paper, we use Chaos theories to analyze the time sequence of gas output, reconstruct the phase space and give the chaos model of output prediction All these are based on the sensitivity of dependence to original conditions and the prediction complexity about output of gas storage in complex mediums of high sulfur content.By optimizing prediction to gas storage as instance, we find that the result is well tally with the real condition, which tells that the chaos model of output prediction of a gas storage is of good reliability and it is practical to the management of gas storage exploitation.