The photoconductivity along the polymer hain direction for poly bis(p-toluene sulpho-nate) ester of 2,4-hexadiyne-l,6-diol (PDA-TS) single crystal is investigated. After analyzing the limitation of Onsager's model for bimolecular geminate pair thermalizing, a new model of photogenerated charge carries is presented and it is used to explain the dependence of stationary photocurrent Iph on the energies of incident photon.