Abstract: Molecular spring is a kind of vibration isolation and shock absorption medium which consists of water and hydrophobic zeolites. In the case of vibration and impact, loading and unloading take turns. Water intrudes into and extrudes from hydrophobic pores of zeolites and at the same time stores, releases and dissipates energy. Force equilibrium of water column in pore and interfacial layer thermodynamic equilibrium are used separately to establish the mechanics model of water intruding into a single hydrophobic pore. Then water flowing into large numbers of hydrophobic pores is calculated considering that contact angle distribution is Gaussian and aperture is uniform. And force-displacement curve of molecular spring is derived. The theoretical result shows good agreement with quasi-static experimental data. Finally, the vibration isolation property is assessed by energy transmissibility. The result shows that the stiffness of molecular spring mixture is piecewise nonlinear with high-low-high three parts and the system with molecular spring isolator has low nature frequency during working. Therefore, molecular spring is suitable for heavy equipment with low frequencies.