According to characters of software project risk management, this thesis, through Lyapunov exponent, proves this system as a chaotic one and makes a study of its chaotic characters. Software project risk system is not only a complex nonlinear system, but also one sensitively dependent on initial condition and a dynamic and open dissipative system. The reason of producing chaos is the uncertainty of project management in enterprise. Based on these chaos characteristics, managers can adopt corresponding management solutions to realize the unification between order and disorder, further improve the software project risk management level and then, realize the object of software project risk management. With various proving methods of chaotic system, this thesis only use Lyapunov exponent to testify. Other methods can also be tried to verify. Making a deep exploration on chaotic characters of software project risk system, this thesis builds a theoretical foundation on the study of software project risk chaotic system. While the further research through theories such as chaotic principles and chaotic dynamics on planning, organization and control of software project risk system under the chaotic environment still waits to be made.