Abstract: Electron beam welding experiment of TA15 ti tanium alloy to 304 stainless steel was carried out.Microstruc-ture and micro-hardness distribution of joint were examined.The results showed that the weldability of electron beam welding of TA15 titanium alloy to 304 stainless steel was so poor that many cracks in the whole weld zone were produced.The weld zone was characterized by a large amount of continuously distributed com-pounds such as TiFe₂,TiFe and Cr₂Ti.The formation of these kinds of brittle compounds was the main reason of the cracks.The micro-hardness in weld zone was much higher than that in base metal.And TiFe₂ phase was harder than TiFe phase,so the throughout crack was found in the TiFe₂-rich zone.Direct elec-tron beam welding of these two alloys was hardly completed.Some interlayer alloys have to be used to improve the metallurgi-cal condition and change the kind and distribution of the com-pounds.