The composite tube of small fixed wing unmanned aerial vehicle is a kind of carbon fiber composite thin-walled laminated tube structure with large aspect ratio， In addition to high internal and external quality and the requirements of unmanned aerial vehicle structure， the internal dimension shall also meet the requirements of subsequent assembly dimension control. Therefore， it is difficult to meet the above requirements by using the traditional prepreg roll forming method. In order to meet the above requirements and obtain a product with simple molding process and good molding quality， a thermal expansion core mold suitable for prepreg molding was prepared by using acrylate rubber and metal core mold， and the process molding of thin-walled laminated circular tube structure products with large length diameter ratio was realized by vacuum bag pressing method with the core mold and metal core mold. The test results show that the thermal expansion and compression of prepreg can be realized by using acrylate rubber as thermal expansion material. The product not only has good internal and external quality， but also meets the requirements of UAV body structure， and its internal dimension also meets the requirements of assembly dimension tolerance control. It is a kind of thin-wall lamination for carbon fiber composites with large aspect ratio and a good forming method for manufacturing round tube.