• Novel three-component conjugated polymers applied in DNT vapor detection. • P1 and P2 present almost instantaneous fluorescence quenching (<90%) to DNT vapor. • The sensors are promisingly applied for on-site and real-time detection to DNT. Two novel three-component conjugated polymers, P1 and P2 , composed of fluorene, carbazole and anthracene / pyrene units, were designed and synthesized. After optimizing the ratio of these three components, their spin-coating films were prepared and used to detect nitro explosives in vapor phase, which present almost instantaneous fluorescence quenching (<90%) and high selectivity to 2, 4-dinitrotoluene (DNT) vapor. Moreover, the films presented outstanding reusability and their simple filter paper sensors have been applied in the visualized detection of DNT, which indicate their promising on-site and real-time detection to DNT. [ABSTRACT FROM AUTHOR]