Modified poly(3-hexylthiophene) (P3HT) with molecule of 1,4-dithienyl-2,3,5,6-tetrafluorobenzene in the main chain was developed as a new class of conjugated polymer with high stability. The structural and optical characteristics of modified polymer were investigated by x-ray diffraction (XRD) and optical absorption spectroscopy. By comparing to characteristic of P3HT, the XRD pattern of modified polymer showed the diffraction peak shifted from theta of 5.4o to 5.9o with decrease intensity. This indicates that the modified polymer chain has a reducing in structural coplanarity and crystallinity. Since the electrical property can be related to the morphology and structure of thin film, the electrical conduction of modified polymer was studied with the structure of ITO/modified P3HT/Al. The result of I-V characteristic measurement of modified polymer as a function of temperatures showed that the conductance decreased with decreasing temperature. The mobility of copolymer was also evaluated by using time of flight measurement and mobility value of 5x10-4 cm2/Vs was obtained at room temperature.