Plasmonic metals possess the ability to enhance the interaction between light and matter, which has been widely used in optoelectronic devices, especially, a direct contact is established between metal and semiconductor in hetero-nanostructure. In this work, we report an enhanced photodetector by surface plasmon, which is based on Au-PbS core-shell nanorod phototransistor. The photodetector achieved higher responsivity of 18.5 A W-1, detectivity of 1.22 x 10(11) Jones and EQE of 2844% under an 808 nm laser illumination. The results indicate that the Au-PbS core-shell nanorods have great potential in optoelectronic devices.