Abstract: In this paper, the problem of plane waves in a thin-walled tube of orthotropic composite under combined actions of extension and torsion are investigated by using the method of characteristics. The wave speeds, the characteristic relations and the general solution of the problem are obtained and a special initial-boundary value problem is solved.The simple wave solutions are also obtained and discussed in detail.The results show that there exist a number of characteristic properties and physical phenomena which differ substantially from those of waves in an isotropic medium. For example, there are two waves in the thin-walled tube of composite, and one can classify them as fast wave and slow wave according to their wave speeds.Each wave is neither extensional nor torsional, but rather a combination of both, Here the extension and torsion are tightly couppled.Hence, a general end loading will produces both waves, not just one of them.