In order to obtain a complete set of materials performance data, and provide support for part manufacturability, and determine whether to meet the requirements of the civil aircraft design and application, the high temperature cured epoxy resin impregnated carbon fiber composites were fabricated by hot press process with two groups of three batches respectively. The prepreg and composite physical properties, basic mechanical properties under three different environment conditions were investigate. The results show that the resin volatiles of this two group prepregs are small, the resin flow and gel time are moderate,so the processes are good. The porosities of two group composites are small, and the fiber volumes are moderate, the temperature resistance, humidity resistance and interface adhesion property of this two group composites are relatively good. The overall mechanical property under three different environment conditions of M21 system composite are better than these of CYCOM 977-2 system composite. The results are all basic to satisfy a certain type of civil aircraft tail box’s design and use requirements, and it provide the basis for the subsequent application of this composites development.