Based　on　the　finite-difference　time-domain　(FDTD)　method,　the　terahertz　(THz)　polarization　characteristics　of　a　metal　wire　grid　structure　are　simulated　and　analyzed.　The　influences　of　duty　ratio　and　metal　layer　thickness　on　the　polarization　characteristics　are　investigated.　It　is　found　that　the　periodic　high　transmission　phenomenon　in　the　range　of　0.1-10　THz　occurs　with　the　increase　of　the　metal　layer　thickness.　The　metal　wire　grid　THz　polarizer　is　fabricated　by　the　femtosecond　laser　micro-machining　technique,　which　is　tested　by　the　time-domain　terahertz　spectroscopy　system.　The　experimental　results　are　consistent　with　the　simulation　ones.　The　extinction　ratio　of　the　polarizer　is　in　the　range　of　40　dB-45　dB　and　the　polarization　degree　is　1,　which　indicates　that　the　polarizer　possesses　a　good　polarization　characteristic.　©　2018,　Chinese　Lasers　Press.　All　right　reserved.