A theoretical model is established in this paper to investigate the micro-particle behavior in the static water. The forces acting on the micro-particles are analyzed to obtain a description of the micro-particle behavior in the static water. It is shown that the velocity of the micro-particles is a function of the diameter of the micro-particles, the density of the fluid and the micro-particles, the viscosity and the time. The micro-particle＇s motion undergoes an accelerating period and a constant velocity period, and the acceleration period of small micro-particles is very short, its velocity is much smaller than that of larger ones. The net flux of a control-volume in the flow field is calculated combined with the Fick Law. It is shown that the transport coefficient is a function of the diameter of the micro-particles, the density of the fluid and the micro-particles, the viscosity and the temperature. The transport of smaller particles is more extended than the larger ones. The digital holography technology is applied to detect the micro-particle＇s motion and the comparison between the theoretical solution and the experimental results is made, with a quantitative agreement between them.
