Abstract: Electron beam welding and local heat treatment is a new combination processing technology.Its temperature and stress fields were computed by finite element method with ANSYS software code, and 2 mm, 6 mm and 12 mm thick TC4 titanium alloy plates were taken as the researched objects.The influence rules of local heat treatment on temperature and stress fields of electron beam welding for different thickness plates were analyzed.It is found that the effect of electron beam local heat treatment of 2 mm thick titanium alloy plate is the best under the given computational condition. Within the distance of 4 mm from the centerline at the surface, cooling rate are almost the same after electron beam local heat treatment. The maximum longitudinal residual stress reduces from 780 MPa to 560 MPa.The decrease amplitude reaches 28%.