The buoyancy principle of magnetic fluid is one of the most attractive effects of magnetic fluid statics. But it is too difficult to calculate the buoyancy directly due to the complexity of magnetic field. Moreover, numerical calculation employs too many assumptions. So in this paper the experimental method is adopted to measure the second-order buoyancy received by permanent magnet immersed in magnetic fluid, which depends on the distance between the magnet and the wall of vessel. The influence of the diameter of cylindrical vessels, the size of magnets and the saturation magnetization of magnetic fluid on the buoyancy is also analyzed qualitatively.