Thermal-induced errors have a significant impact on the environmental adaptability of a fiber optic gyroscope (FOG). Reasonable winding methods can reduce and offset the thermal-induced errors. However, complex methods put higher requirements on winding accuracy. By adding additional winding layers on the outer surface of the fiber coil, an improved winding method to reduce the temperature error of FOG is proposed in this paper. Simulations in temperature-control conditions and time-varying temperature conditions are performed. Simulation and experimental results show that additional winding layers lead to a satisfactory reduction of thermal-induced rate errors. With parameter estimation and error compensation, thermal-induced errors can be further reduced.