<p>Hydro-pneumatic near-zero frequency (NZF) vibration isolators have better performance at isolating vibration with low frequencies and heavy loadings when the nonlinear fluidic damping is introduced and the pressurized gas pressure is properly adjusted. The nonlinear characteristics of such devices make their corresponding dynamic research involve chaotic dynamics. Chaos may bring negative influence and disorder to the structure and low-frequency working efficiency of isolators, which makes it necessary to clarify and control the threshold ranges for chaos generation in advance. In this work, the chaotic characteristics for a class of hydro-pneumatic NZF vibration isolators under dry friction, harmonic, and environmental noise excitations are analyzed by the analytical and numerical methods. The parameter ranges for the generation of chaos are obtained by the classical and random Melnikov methods. The chaotic characteristics and thresholds of the parameters in the systems with or without noise excitation are discussed and described. The analytical solutions and the influence of noise and harmonic excitation about chaos are tested and further analyzed through many numerical simulations. The results show that chaos in the system can be induced or inhibited with the adjustment of the magnitudes of harmonic excitation and noise intensity.</p>