Static load tensile test is the most widely used mechanical properties test. In this paper, it is tried to reveal that the influence of the presence of laser welded joint on the deformation behavior of the specimen by comparing the thermal effects of TC4 base metal and joint specimen during tensile test by infrared thermograph method. The results show that for joint and base metal specimens with the same tensile strength, there are many differences in the thermal effect, such as the beginning times of the physical yield phenomenon and the corresponding stresses, the temperature distribution and evolution process.