The Computer Simulation Model of the Socio-Economic and Ecological System of the "CROATIA"-SEESC had been developed in accordance with the System Dynamics Approach. It is a continuous model and at the same time discrete digital model because it is presented as a system of non-linear differential equations and it is presented as a system of difference equations (System Dynamics DYNAMO-software program-package) and its “DT” (length of intervening time = computation interval) is chosen in full accordance with the Sampling Theorem (Shannon and Koteljnikov). In this paper the authors have presented the principles of the application possibilities of the System Dynamics Modeling Approach on the Socio-Economical and Ecological Systems of Croatia. Further, they have conducted elementary observations on the Socio-Economic and Ecological Systems of CROATIA-SEESC, their four regional parts (CMZSR, CSOSR, CNWACRSR and CDACSR), the Space and Environment Sector-SES of the CDACSR, and the high aggregated structural models of the SES, ecological model of the CDACSR, and rudimentary global model of the SEESC. The developed model covers period from years 1953 to 2033, with inbuilt war situation (1990-1995).