The substrate was the installation basis of solar cell for spacial solar array. "Upper and lower grid panel of carbon fiber composite + aluminum honeycomb core + polyimide film" was a typical structure of the substrate. As the key raw material of the solar array， high-modulus carbon fiber must be autonomous and controllable. To this end， the research of domestic high-modulus carbon fiber CCM40J-6K/epoxy composite applied to solar array''s substrate had been carried out. And three key links， including macro mechanics， pull-off resistance of micro mesh， and adhesion performance of polyimide film of CCM40J-6K/epoxy composites in substrate applications， had been proposed. Five aspects of testing and verification items， including mechanical properties， bonding force of mesh panel node， bondingperformance of polyimide film， and thermal-cycle performance of substrate structures， had been carried out. The verification results show that the mechanical properties of solar array''s substrate using the domestic carbon fiber-CCM40J-6K are equivalent to those of the imported M40JB-6K， and the original related molding process of substrate by M40JB-6K can be followed. Test pieces of single-layer and multi-layer laminate substrate can withstand thermal shock and thermal cycling tests， whose mechanical properties have no obvious change before and after the test， and the polyimide film has no debonding phenomenon. The tensile strength of the grid node of the domestic carbon fiber is 18.9% higher than that of the imported carbon fiber. It shows that the domestic carbon fiber CCM40J-6K can be applied to the development of the substrate structure for solar array.