Abstract: An acceptor-π-acceptor(A₁-π-A₂) conjugated polymer(PPPD-DPP) based on 6-alkylpyrroles3,4-dpyridazine-5,7-dione(PPD) and diketopyrrolopyrrole(DPP) units was synthesized by Stille cross-coupling reaction.The thermal,optical, electrochemical and transistor properties of the polymer were studied by thermogravimetric analyzer,UV-Vis-NIR absorption spectrophotometer and cyclic voltammetry.The polymer PPPD-DPP showed excellent thermally stable with a decomposition temperature of 376℃ and broad absorption in the near infrared region.PPPD-DPP also had low band gap of 1.27 eV and deep highest molecular orbital energy level(HOMO) of -5.23 eV.Polymer-based organic thin film transistors(OTFTs) devices exhibited ambipolar charge transport under vacuum and yielded the mobilities of 0.030,0.054 cm²/(V·s) for electron and hole,respectively.The devices were also investigated in air and diaplayed p-type transport behavior with a hole mobility of 0.121 cm²/(V·s).