The present invention is to provide a method for encoding and decoding serial signals formed by a plurality of color lights, which is applied to an encoding/decoding system comprising an encoding device and a decoding device, and comprises steps of generating a driving signal corresponding to at least one first serial code set by the encoding device, so as to drive a multi-color LED to generate a plurality of color lights having different wavelengths and interval time of flash intervals; and receiving the color lights by the decoding device, decoding the color lights according to a decoding procedure of the decoding device for obtaining the first serial code set, and sending an actuation signal when determining that the first serial code set is identical to a second serial code set, so as to provide a variety of more sophisticated, safer and uneasy interfered encoding/decoding functions to various wireless control procedures.