The utility model discloses a pipe cleaner capable of automatically adjusting bypass rate, which comprises an elastic body capable of automatically and finely adjusting the bypass rate according to pressure, and a central channel of the elastic body penetrates through two opposite ends of the elastic body to form a bypass channel; the dirt removing assembly is used for removing pipe wall attachments and is arranged at the first end of the elastic body; the discharging structure is arranged at the second end of the elastic body; an annular cavity which surrounds the bypass channel and is isolated from the bypass channel is formed in the wall of the elastic body, the discharging structure is communicated with the annular cavity, and gas in the annular cavity is discharged so that the bypassrate can be reduced to zero. According to the pipe cleaner capable of automatically adjusting the bypass rate, the bypass rate can be automatically adjusted along with the change of the front pressureand the rear pressure of the pipe cleaner during pipe cleaning, so that the pushing force of the pipe cleaner and the liquid plug amount in front of the pipe cleaner are changed; once large resistance is encountered, the bypass rate can be automatically reduced to zero through the discharging structure, it is guaranteed that the pipe cleaner has enough pushing force, and continuous and stable advancing of the pipe cleaner during pipe cleaning is guaranteed.