Abstract: A symmetry-common recursive architecture of IMDCT is proposed based on digital audio decoder in this paper.The architecture uses the parallel and recursive property of IMDCT sufficiently.It accords with modularization and regularity of the hardware system architecture and can realize the time-sharing calculation on odd or even data.The symmetry of IMDCT is considered concurrently，so that the calculation load is reduced greatly and the complexity of hardware is reduced as well.