Abstract: A regioregular and permeable conjugated polymer was synthesized and studied and employed in Methamphetamine （MA） Vapor Detection. The regioregular polymer structure and the incorporation of big sterically hindered groups could both increase the effective sensing sites in polymer films for MA molecule by providing more cavities for MA molecules and improving the permeability of polymer films. Besides,the incorporation of big sterically hindered groups could also decrease the π-π stacked interchain interaction between polymer chains which usually causes a decrease of self-quenching in polymers. In addition to the good fluorescent quantum efficiency and photostability,the regioregular and permeable conjugated polymer showed excellent response in 300 s with a fluorescent enhancement of 106%.