Abstract: The additional stress system of mass is a complex and nonlinear system with credibility, randomicity and internal randomicity. Chaos experiments are designed to further reveal the characters of additional stress system. Not only large number of develop patterns about the additional stress system are obtained; the system is also verified to be an Chaos system with main development pattern through the Chaos calculation from the experimental data. A theory models are established based on the theory analysis and the experimental results which describe the Chaos characters of the soil additional stress system.