A method and device for interleaving the (N+1) input data and for allocating the corresponding memory comprises the steps of allocating a mth buffer section equals to (m×Dm+Pm) memory address for buffering the mth data of the N+1 input data, where m is a nonnegative integer from 0, 1 to N, Dm is the delay of the mth data, and Pm is a nature number representing a predetermined number of memory address for extra buffering the mth data; assigning an empty memory address in the mth buffer section to buffer the mth data; accessing the mth data from where the mth data buffered after buffering the (N+1) data, and outputting the (N+1) data in a (m×Dm) delay sequence. The present invention allocates the memory address effectively, so applying the present invention economizes the use of the memory request.