We explore the effect of high-speed blade coating on electrical characteristics of conjugated polymer-based thin-film transistors (TFTs). As the blade-coating speed increased, the thickness of the polymer thin-film was naturally increased while the surface roughness was found to be unchanged. Polymer TFTs show two remarkable tendencies on the magnitude of field-effect mobility with increasing blade-coating speed. As the blade-coating speed increased up to 2 mm/s, the fieldeffect mobility increased to 4.72 cm²V-1s-1. However, when the coating speed reached 6 mm/s beyond 2 mm/s, the field-effect mobility rather decreased to 3.18 cm²V-1s-1. The threshold voltage was positively shifted from 2.09 to 8.29 V with respect to increase in blade-coating speed.