To improve the situation of dust concentration exceeds in crushing chamber and obtain rational parameters for the design of dust removal by ventilation, due to the similarity theory and the motion equations of gas-solid two-phase flow, the similarity index was educed and a similarity model device was designed for the specific situation in the crushing chamber. Furthermore, the dust concentration distribution of similarity model in crushing chamber was simulated by using software named Fluent. After the comparison with similar experimental data analysis, the result showed that the simulation result was consistent with the experimental data. Therefore, the results indicated that dust concentration in chamber under trap wall condition is lower than it under the reflect condition. When the wind velocity at entrance was in the range of 0.2 m/s to 0.5 m/s, dust concentration gradually reduced with the increasement of wind velocity. Finally, after the installation of downdraught dedusting system, the dust concentration was below 2 mg/m³, and the average removal rate reached 90%.