Micromotors with self-propelling ability demonstrate great values in highly sensitive analysis. Developing novel micromotors to achieve label-free multiplex assay is particularly intriguing in terms of detection efficiency. Herein, structural color micromotors (SCMs) were developed and employed for this purpose. The SCMs were derived from phase separation of droplet templates and exhibited a Janus structure with two distinct sections, including one with structural colors and the other providing catalytic self-propelling functions. Besides, the SCMs were functionalized with ion-responsive aptamers, through which the interaction between the ions and aptamers resulted in the shift of the intrinsic color of the SCMs. It was demonstrated that the SCMs could realize multiplex label-free detection of ions based on their optical coding capacity and responsive behaviors. Moreover, the detection sensitivity was greatly improved benefiting from the autonomous motion of the SCMs which enhanced the ion-aptamer interactions. We anticipate that the SCMs can significantly promote the development of multiplex assay and biomedical fields.