We have fabricated Surface Plasmon Polariton (SPP) enhanced ZnO based Metal-Semiconductor-Metal (MSM) photoconductive UV detectors with the introduction of Ag nanoparticles. The absorption spectra show two SPP resonance peaks located at 321 nm and 389 nm, respectively. Annealing in Ar atmosphere leads to a red-shift for the long wavelength peak due to an increase of the average size of Ag particles and congregation of them. The experiment data agrees well with the computing result based on Mie theory. And the responsivity enhancement is demonstrated by the fact that the peak responsivity (at 350 nm) increases by more than 100 times, from 472 mA W-1 to 51.3 A W-1. (C) 2013 Elsevier Ltd. All rights reserved.