By means of finite element,stress field theory of TC4 titanium alloy and YG8 cemented carbide vacuum brazing process have been studied. According to the conduction equation,boundary conditions and initial conditions,the stress field was simulated.Using abaqus6.11 software platform,nickel-based solder as an example,based on the Mises stress-strain criterion to calculate the post-weld residual stress level,a conclusion can be drawn that the main residual stress exist at the side of hard alloy,and its maximum is 1328 MPa. So the cracks causing by thermal stress should exist the position of maximum stress,and this theoretical result is consistent with experiment result. The test results show that the finite element analysis has important guiding significance for the crack control at the welding seam during the vacuum brazing process.