Scale factor is a key indicator for evaluating the dynamic performance of fiber optic gyroscope, its error directly affects the precision and stability of fiber optic gyroscope. Because the area of the gyroscope fiber optic sensing coil is positively related to the temperature due to the thermal expansion and cold contraction effect, a linear compensation method is proposed to compensate the gyroscope scale factor error using the temperature characteristics of the light source, which makes the temperature compensation effect of the subsequent fiber optic sensing coil is the best. The experimental results show that, in the range of 100 ℃ (- 40~+60 ℃), the scale factor error of fiber optic gyroscope is reduced from 1100ppm to 620ppm after using this method, which greatly improves the temperature stability of fiber optic gyroscope scale factor (before temperature compensation of fiber optic sensing coil).