The power attenuation coefficient and the change of the coherence of the laser through the sediment-laden water are obtained in the experiment. In dynamic state the velocity of the sediment-laden flow and Doppler signal characteristics are measured. The optimum concentration and the limitation concentration of the sediment-laden flow for laser Doppler anemometer are obtained. The analysis of dynamic experiment using a simple model is connected and the results of the analysis agree with those of the experiment.