The invention discloses a transcoding method used for similar video code streams, which comprises the following steps: firstly, analyzing sound code stream data, namely extracting video data from the file format, analyzing according to the sound code stream format, obtaining the parameter and the transformation control parameter which an existing decoder needs, secondly, transforming the sound code stream data, namely transforming the sound code stream data according to transformation control information, thirdly, resetting a sound code stream, namely carrying out the corresponding format arrangement to the data which is transformed in the second step or data which is directly transmitted according to the requirements of the format of a target code stream, and then obtaining the target code stream needed by the existing decoder. The method greatly expands the use range of an existing decoder in maximum, fully utilizes the existing decoder, and improves the availability ratio of a device with a decoder, in particular to an inlaid device with the hardware decoder.