With computational fluid dynamics and physical properties of radon, a three-dimensional steady-state transport model of radon in a blind roadway with a chamber is established. The control equation is calculated with software Fluent. Radon exhalation and decay in the inner wall of the roadway are realized with UDF. Wind field structure and radon concentration distribution in roadway are obtained. It shows that when the ventilation rate is constant, temperature has a significant effect on radon concentration. The higher the temperature in the roadway, the higher the radon concentration in the roadway. Radon concentration of the chamber is the greatest in the whole roadway. Compared with radon prevention enclosure, local ventilation is better for reducing radon. As pressure ventilation is adopted, radon concentration in the roadway increases from inside to outside.Improving ventilation rate of the tunnel reduces effectively radon concentration at the entrance of the tunnel, while it has little effect on radon concentration in the chamber.