Investigation of relationship between the temperature in optical fiber and transmission characteristics is very important for the design and application of fiber composite low voltage cable(OPLC). A two-dimensional simulation model was established using COMSOL multi-physics simulation software to study the change of fiber axial stress with temperature, and the rationality of the model is verified by comparison with theoretical calculation. The stress elastic coefficient of quartz fiber was calculated theoretically and the transient temperature rise characteristics and thermal strain loss of the two kinds of optical fibers, acrylic and polyethylene, were analyzed by simulation based on the photo-elastic effect. The results show that the optical fiber with coating material of acrylic resin has smaller transient temperature rise in same time and lower loss at the same temperature. And its thermal strain loss increases linearly with increasing temperature in the range of 40°C to 250°C, with a maximum of 0.033 dB/km. From the viewpoint of transient temperature rise and thermal strain loss, the optical fiber with the coating material of acrylic resin is of more advantages in the application of OPLC.