Abstract: During the last 20 years, there have been vast researches and developments on composite materials, especially on their raw materials and their end uses. But, the literature of design philosophy is relatively rare. The status of structural design is merely at the so-called "replacement design' stage.From the designer's point of view, the author would discuss some fundamental considerations on structural composites. First, the properties of composites can be tailored. Next, the configuration of structures is unrestrained. The last consideration concerns the linear elastic properties and wide scatter of strength.In order to make a good structural design of composite materials, it is necessary to be clear on the external loading and environment conditions, and obtain the allowable data from large sample testing. Then, the designer has to analyze the worst conditions that the structure is capable of sustaining.