The invention relates to the technical field of panel thickness laser detection, in particular to a C-shaped frame mechanism and an adjusting use method capable of improving laser on-line thickness measuring precision. The C-shaped frame mechanism comprises a C-shaped frame shell body, an upper laser sensor, a lower laser sensor, an upper angle moving platform group, a lower angle moving platform group and a lower displacement platform group. The C-shaped frame mechanism corrects technical bias that laser which is emitted by the upper laser sensor and the lower laser sensor and an injection angle of a measured object can not affect detection precision, due to the fact that a special adjusting device is arranged on lower positions and lower positions of two laser sensors which are used for collecting data and arranged at the front end of a C-shaped frame, a physical characteristic that a light ray can display a light beam path in turbid liquid is utilized, then the laser sensors are adjusted. Therefore, in static and dynamic states, detected data by an upper laser sensor and lower laser sensor can achieve the best measurement accuracy of the sensors.