A ranging system and a mobile platform are provided. The ranging system includes a laser, a coaxial optical lens group, a mirror group, a moving component, and a processing circuit. When the laser emits laser light to the mirror group by using the coaxial optical lens group, the moving component drives the mirror group to rotate, so that the laser light is irradiated to a measured object at different angles, to implement ranging of the measured object. The moving component bears a light object, so that the moving component rotates quickly. Therefore, if the ranging system is installed on a vehicle, the ranging system can implement fast ranging of incoming and outgoing vehicles and meet a ranging requirement of an autonomous driving technology.