A blind recognition method of channel coding based on soft information was proposed for packet interleaver and convolution code in a non-cooperative digital communication system.The method builds conformity degree concept using the soft information.It identifies the row number of interleaving matrix and the parity-check vector of convolution code by using the total conformity degree of the sample sequence.And the row coordinate of starting point is identified by the change rule of average conformity degree of each sampling sequence.Finally

the column number of interleaving matrix and the column coordinate of starting point are recognized according to the conformity degree of de-interleaved data.Simulation results show that the proposed method provides an optimal performance in the noisy environment

and has 5dB SNR gain when achieving the relatively high accuracy compared with the recognition algorithm based on hard information.