Based on the theory of probability

with a small cloth bag in the catalyst bound as the study object

the model of tracer concentration distribution in the fixed bed was established using the traditional Galton board model

and the expression of the concentration distribution model in the fixed bed was obtained.The experimental setup was established using KCl solution as the tracer and the experimental results were compared with the model predicted values.The experimental value fitted well with the model predicted value.The influences of different parameters on concentration distribution in the fixed bed were analyzed.The trace concentration distribution curve gradually became gentle with increasing catalyst particle size and increasing height of the fixed bed but decreasing liquid spray quantity.