Abstract: To study the impact of metro interval tunnel supply-exhaust combination fans on flow field in main roadway,taking the interval between Dayang station and Qingdaobei station of Qingdao Metro Line 8 as an example,a metro tunnel ventilation model experiment system is constructed with dimensionality analysis and theory of similarity. In this system,the simulation of fire condition is done by the discharge of cold smog,exhaust smog test is conducted,and real-time sampling data is collected. The impact of fan combination and power frequency input on the performance of supply-exhaust combination fans is analyzed.Field data shows that:（1）in the scenario of Two Supply fans（TS）,regular fluctuation of average velocity exists in both sections of the main roadway;（2） in the scenario of Two Supply fans combined with One Exhaust fan（TSOE）,the increase of average velocity in the roadway section with smaller velocity is more sensible than in the other section;（3）in engineering design,TSOE type interval tunnel supplyexhaust system is recommended to be firstly considered,for improving the safe evacuation of drivers and passengers in disaster period.