The present disclosure relates to vehicle technology, and more particularly, to an unmanned vehicle and its sensor device and cleaning mechanism. The cleaning mechanism includes: a housing, a cleaning element, a driving component transmissively connected to the cleaning element and a control unit installed within a receiving cavity. The housing has a light transmissive element provided on a side surface thereof. The cleaning element is pivotable about one end thereof and mounted to the housing. The cleaning element, when pivoting, frictionally interacts with a surface of the light transmissive element that is away from the receiving cavity to clean the light transmissive element. The control unit is communicatively connected to the driving component for controlling the driving component. The cleaning mechanism can clean the light transmissive element using the cleaning element, so as to solve the problem in the related art that a sensor may not function normally due to contamination of a sensor device by dirt such as dust.