The invention discloses a vehicle-mounted pavement crack detection system verifying device based on gear driving and aims at solving the verifying problem of a width variation crack detection result of a vehicle-mounted pavement crack detection system. The vehicle-mounted pavement crack detection system verifying device based on gear driving is mainly composed of a base (1), a bearing seat (2), amotor (3), a clockwise triangular prism rotary shaft (4), a counter clockwise triangular prism rotary shaft (5), a straight gear (6) and a bearing (7). The system provides a vehicle-mounted pavement crack detection system verifying device based on gear driving which is small in space occupation, simple in structure, high in verifying precision, easy and convenient to operate, easy to mount, low incost and reliable in property.