Laser transmission microjoining of two dissimilar materials has become a very significant technique. In this research, a numerical method is developed using finite element technique to determine the condition of joining two dissimilar materials namely Polyethylene terepthalate (PET) and titanium. First the model is used to optimize the laser parameters like laser traveling speed and power to obtain good bonding. A good combination is achieved at the power of 8W and laser traveling speed at 150mm/min.After the verifications, the profile of residual stress of the laser microjoint has been calculated using the developed model. The residual is low near the centerline along the traveling laser beam, and a higher values is away from the centerline at the x-direction shown by the contours on the PET surface. Higher residual von Mises stress near the centerline along the traveling laser beam and the stresses reduce as the distance away from the centerline.