Disclosed in the present invention are a terminal for channel codes, and a method and a device in a base station. The base station sequentially executes channel codes and sends a first wireless signal. A first bit block is used for the input of the channel codes. The channel codes are based on polar codes. The output of the channel codes is used for generating the first wireless signal. The first bit block comprises bits in a first bit subblock and bits in a second bit subblock. A value of the first bit subblock is related to the number of bits in the second bit subblock, or the value of the first bit subblock is related to the number of bits in the first bit block. The position of a bit in the first bit subblock in the first bit block is determined by default. The present invention has the advantages: the blind detection burden of a user equipment is reduced and a more flexible information transmission format is supported.