The invention discloses a method for improving performance of an organic thin-film transistor (OTFT). The method comprises steps of cutting a P-type doped silicon sheet of silicon dioxide into small sheets; cleaning and drying the small sheets by deionized water, acetone and ethyl alcohol; dropping OTS on the small sheets; coating mixed solution of OTFT new type active layer material BFTII and the classic material P3HT in a spinning manner; and then performing thermal annealing. According to the invention, manufacturing cost is low and technology is simple; by doping polymers on and performing thermal annealing on the new type oligomeric OTFT active layer material, even if the OTFT is kept in quite low threshold voltage, carrier mobility can be increased by more than two order of magnitudes and the switch ration can be increased by one order of magnitude; and the method is widely applicable for industrial application.