In order to enhance the performance of poly(3-hexylthiophene) (RR-P3HT) organic field-effect transistors (OFET) by low temperature solution-process of non-solvent addition (acetonitrile and ethanol), the resulting self-organization of polymer semiconductor layer and performance of RR-P3HT OFET are studied in this paper. The results fshow that an appropriate non-solvent addition (acetonitrile and ethanol) promotes the formation of more microcrystalline lamellae and improves the self-organization of polymer semiconductor layer, resulting in electrical properties enhancement of polymer OFET. The results indicate that the field-effect of RR-P3HT OFET with 5% acetonitrile addition can reach 3.39×10-3 cm2/V ·s, which is higher by a factor of 8 than that with 0% acetonitrile addition. Encessive non-solvent addition (acetonitrile and ethanol) leads to more precipitates which reduce microcrystalline lamellae and lowers the quality of polymer film, resulting in performance degradation of polymer OFET.