A Two-Unit system with connecting and disconnecting effect is studied in this paper. By the method of Functional analysis strong continuous semi-group, the paper analyzes the restriction of essential spectral growth bound of the system operator. The restriction of essential spectral growth bound of the system operator and the change of the essential spectral radius after perturbation is analyzed. The essential spectral radius of the system operator is also discussed before and after perturbation. The results show that under some conditions the dynamic solution of the system is exponential stability and tends to the steady solution of the system. At last, we analyze the reliability of the system.