The applications of Laser particle size analysis in sediment fields have been developed in recent years. Some factors such as the weight of the sample and dilution affect the measurement result of laser particle size analysis. For Micro S3500, the optimum weight of a sample is about 0.2 grams. If diluted, it affects the result of the particle size distribution. The method of sampling causes different random errors. Compared to the particle size distribution parameters (average size, standard deviation, skewness and kurtosis), the results obtained by laser analyzer show a smaller average size than the image method and sieving method. However, a good correlation for kurtosis was observed between the laser method and sieving method.