Microstructures　of　electron　beam　welded　joints　for　TA15　titanium　alloy　with　different　hydrogen　contents　were　observed　and　analyzed　by　SEM　and　TEM.　And　the　influence　of　hydrogen　on　microstructure　of　the　joints　was　investigated.　The　results　show　that　the　microstructure　of　the　weld　metal　is　lamellar　alpha+beta　phase　after　hydrogen　charging.　In　the　range　of　hydrogen　contents　discussed　in　this　study　(from　0　to　0.101　wt%),　With　the　increase　of　hydrogen　content,　there　is　little　change　in　the　appearance　of　the　microstructure　of　the　weld　metal.　The　presence　of　hydrogen　can　promote　the　growth　of　twins　in　electron　beam　welded　joints.　With　the　increase　of　hydrogen　content,　the　number　of　twins　is　increased.　When　hydrogen　content　reaches　to　a　certainty　level,　hydrides　are　found　in　TA15　electron　beam　welded　joints.