An encoding method, a decoding method, an encoding device and a decoding device are provided. The encoding method includes: obtaining a first bit stream of an original encoded data; determining whether a number of the successive bits is greater than a predetermined number; if the number of the successive bits is greater than the predetermined number, then selecting at least one target bit from the successive bits; performing a logic NOT operation on the target bit to obtain a symbol bit; and inserting the symbol bit to the successive bits to obtain an encoded bit stream. The present disclosure could raise the encoding speed and reliability.