This paper, reports the synthesis of an alternating, copolymer consisting of dithienosilole (DTS) and thienopyrroledione (TPD) units via palladium-catalyzed direct arylation polymerization (DArP). Although DArP has recently attracted much attention as an easy synthetic method of pi-conjugated polymers without the need for prepreparation of organometallic monomers, there are two major problems that must he eliminated. One is homocoupling producing structural defects in the polymer chain, and the other is by production of insoluble materials. In this study, we have found that the combined use of P(2-MeOC6H4)(3) and P(2-Me2NC6H4)(3) ligands effectively prevents these side reactions, resulting in poly(DTS-alt-TPD) (M-n(GPC) = 15000, M-w/M-n = 2.57) with good solubility in high yield (84%).