[en] The degradation behavior of composite materials due to each important environmental factor has been investigated for the purpose of establishing the techniques of environmental durability assessment for composite materials. The combined space environmental effect facility has been developed based on those systematic data on the evaluation of advanced composite materials such as carbon fiber-reinforced plastics (CFRP) using epoxy resin as the matrix in space environment. The facility was designed and assembled for simulating space environment, and it has the functions of thermal aging, heat cycle, far ultraviolet ray irradiation and electron beam irradiation being applicable in high vacuum and at high loading. Further it can analyze evaporated gas in situ with a gas mass analyzer. The facility houses a universal tensile testing machine so that the mechanical properties of composite materials can be measured directly in space environment. The examples of the results of measurement of CFRP with the gas mass analyzer, the change of mass number and temperature by aging time or electron beam irradiation in vacuum and so on are shown. (K.I.)