Twin Rotor MIMO System (TRMS), an aerodynamic experiments system of high nonlinearity, induces two inputs, two outputs and six state parameters. In the world, this system has been studied, applied to evaluate and implement advanced control techniques. However, in Vietnam, the TRMS is installed at a number oflaboratories at Universities, but it has hardly been used for testing modem control algorithms, because there is no exact mathematical model of systems. This paper shows the survey results, a mathematical model of TRMS system was built, simulation results shown clearly the influence of the parameters to the status of systems. These results are compared with real objects that it show clearly the accuracy of the model and can be used as a basis for further researches.