Influence of heating modules such as light source and accelerometer in inertial measurement unit（ IMU） on temperature field distribution of fiber coil is analyzed from structure perspective

finite element model（ FEM） for a certain type of three-axis integration optical fiber gyro strapdown inertial navigation system（ INS） is established. Analyze and study heat transferring rule of IMU under the condition of room temperature（ 22 ℃） and steady state

which indicates that the heat generated by light source and accelerometer can not be transferred from box to IMU in the way of heat conduction

and influence of convection and radiation on temperature field distribution of IMU is great. Light source is the principal heating source which is the main reason affects nonuniform of temperature distribution of Y and Z axis fiber coil

and temperature distribution of fiber coil in X axis is influenced by heating of accelerometer. Through high temperature（ 60 ℃） trans thermal analysis

study on temperature variation rule of fiber coils under the condition of extreme environment

it indicates that temperature gradient declines when temperature rises

fiber loop transient temperature difference increase in harsh environment. Both steady and transient thermal analysis can guide improvement of thermal designs of IMU paitial structure of INS.