Fatigue　life　of　BT20　Titanium　alloy　sheet　and　its　laser　beam　welded　joints　was　evaluated　experimentally.　The　mean　fatigue　life　of　the　joints,　under　various　stress　levels,　was　obtained.　The　lower　band　life　of　lease　beam　welded　joints,　with　a　survival　probability　of　99%　and　a　confidence　level　of　95%,　was　also　obtained.　The　effect　of　welding　condition　on　the　fatigue　life　of　the　joints　was　analyzed.　It　was　found　that　the　fatigue　life　of　the　joints,　either　welded　by　conventional　leaser　beam　or　by　active　leaser　beam,　is　lower　than　that　of　the　base　metal.