Abstract: A novel fluid-type floating raft vibration isolator based on anti-resonance principle is designed in this paper. The mathematical model of the floating raft is built based on the fluid momentum equation and the vibration theory. The isolation behavior of the floating raft is analyzed. The relationship between the optimum isolation frequency and the immersed depth of the floating body is obtained. It is found that the anti-resonance occurs over a wide band from lower to higher frequencies with the immersed depth of the floating body in a limited range. Utilizing the anti-resonance, the force transmissibility of the fluid-type floating raft can be reduced at very low levels. The raft enjoys an excellent performance of vibration isolation especially for low frequency vibrations.