Abstract: A one-meter-level carbon fiber reinforced plastic(CFRP) composite antenna panel with the surface error less than 10 μm root-mean-square(RMS) has been trial-produced by using additional resin modification technology to satisfy the requirements of high frequency antenna reflector in submillimeter and terahertz wave band. The thermal deformation mechanisms of the high accuracy CFRP composite panel under extreme low temperature were studied. Based on the test data of the basic material, a finite element model was established to predict the thermal deformation residual error of the the panels considering different parameters under the condition of large temperature difference. The main factors affecting the thermal deformation characteristics of the panel were analyzed. The thermal deformation characteristics of the panels with aluminum honeycomb and CFRP composite tube array cores were compared, respectively, which shows that the higher specific stiffness and thermal stability are provided by the panel structure with CFRP composite tube array core. The structural design parameters of the prototype panel were given after the structural optimization, and the prototype panels were remanufactured. The thermal deformation residual errors of prototype panels with aluminum honeycomb and CFRP composite tube array cores were measured by the experimental method of high precision photogrammetry. The guidance for the design and process of high accuracy CFRP composite sandwiched panels was provided.