A kind of organic field-effect transistor(OFET) is fabricated with poly-methylmethacrylate(PMMA) as the gate insulator and pentacene as the active layer.Compared with traditional OFETs which have single layer source/drain electrode,our transistor has double-layers S/D electrode.The results demostrate the performance of OFET can be improved obviously by using such double-layers electrode. Then,OFET can be operated with the mobility of 0.133 cm2/Vs and the on/off current ratio of 2.61×105.The role...