Abstract: HgCdTe plane array detector is a key component in infrared space camera. The scale of detector is enlarging continuously due to the unending requirements of better performance. HgCdTe plane array detector needs to be mounted on loading board in room temperature, and it needs to work at deep cooling environment, temperature fluctuation at about 200 K should be endured. Temperature fluctuation leads to warping deformation of detector due to mismatch of CTE between detector and loading board, and large warping deformation results in damage in detector. Then thermal adapter of HgCdTe focal plane arrays based on carbon fiber with high heat conductivity was proposed. High axial heat conductivity of carbon fiber was adopted to reduce thermal resistance of adapter, and minimal section bending modulus of carbon fiber was adopted to decouple the stiffness between two end faces of thermal adapter. Compared with direct bonding assembly between detector and loading board, after the adoption of thermal adapter based on carbon fiber with high heat conductivity, thermal resistance between detector and loading board was increased by merely about 1 percent, but warping deformation of detector due to mismatch of CTE was reduced by more than 99.9 percent. Problem of damage on large scale detector due to mismatch of CTE was resolved. Manufacture process of thermal adapter based on carbon fiber was briefly introduced.