The invention discloses a method for interleaving and deinterleaving a convolution in digital transmission. The method regards an RAM as a ring with end-to-end addresses, and occupies RAM I(I+1)M/2 space while interleaving according to the I and M information. While interleaving, the RAM is subject to writing-after-reading operations round by round. Differences among various addresses that are read and written in each round are M, 2M, to IM, and the address of the next round is close to that of the prior round. RAM I(I+3)M/2 space is occupied while deinterleaving, and reading-reading-writing operations are performed round by round. Differences among various addresses that are read for the first time in each round are (I+1)M, IM, to 2M, and the address of the next round is close to that ofthe prior round. The address that is read for the second time and the address that is read for the first time are separated by 2M+1 space, namely having a distance of the 2M (shown as in the figure).The written address is the same as the address that is read for the first time. The convolution process is simply controlled, and a deinterleaver and an RS decoder can share an RAM, which saves the resources.