Using similar proportional model test, the effects of different dust particle size, initial dust volume and return air rate on dust transport characteristics are explored based on the standard cross section of a long double-track railway tunnel. The results show that: With the increase of dust particle size, the peak dust concentration in the section shows a linear decrease, and the larger the dust diameter is, the more obvious the diffusion effect is driven by the wind flow field. The effect of initial dust concentration on dust transport mainly shows that with the increase of the concentration field. The peak concentration rises, the dust spreading rate decreases, and the diffusion effect by wind flow is relatively small. With the increase in longitudinal wind speed, the peak concentration in each monitoring section decreases, and the peak time appears earlier. Meanwhile, the reduction rate of section concentration is enhanced to a certain extent. The hysteresis effect of dolly on dust diffusion is positively correlated with the initial dust concentration of dust particle size, and negatively correlated with the longitudinal return wind speed; the peak dust concentration can be effectively reduced when the return wind speed of engineering operation section is 1.0 m/s.