Vibration isolation is an important method of spacecraft vibration control, and the theoretical study of the isolators' dynamic characteristics is an important foundation to design a specified isolator. In this paper, a new type of micro-vibration isolator which contains viscous fluid is investigated. Based on the Non-Newtonian fluid property, macroscopic heat transfer characteristics of the isolator and the axial vibration behavior of a typical launch vehicle-satellite system, two nonlinear thermo-vibration coupling models of the isolator and the launch vehicle-satellite-isolator system during the launch stage are firstly proposed. Then the damping coefficients and volumetric stiffness coefficients under different temperature environments are measured with the self-designed base excitation test-setup, and these parameters are input into the above models to conduct a simulation. The results show that the behavior of the vibration isolation system is nonlinear and time-variant, and the fluid temperature increase which comes from the viscous heating can lead to a shift of resonant frequency and a fluctuation of resonant amplitude. Moreover, the performance of the isolator is also closely related to the excitation amplitude and excitation frequency, and two new conceptions, i.e., resonant band and isolated band, should be utilized to design the detailed interior structure. Thus the presented theory and method can provide a reference and a theoretical basis for the thermo-vibration coupling characteristics evaluation, optimal design and engineering application of this type of fluid micro-vibration isolators.