The entropy theory is applied to determine the development state of a small scale CELSS (Closed Ecological Life Support System) and the extended Lotka-Volterra ecological model to test its development process. The change of exergy was found to be correlated with the developmental state of CELSS. In addition, two different kinds of asymptotical steady state are obtained from the simulated results and discussed mathematically. The simulation model is considered appropriate for the study of the developmental state and processes for the formulation of CELSS.