Lens back focus measuring device

The utility model provides a lens back focus measuring device. The lens back focus measuring device comprises a calibration plate, a base, a light source module, a clamping and displacement module andan imaging module. A support is vertically fixed to the base, and a plurality of connecting rods distributed at intervals are fixed to the support. The light source module is fixed to one of the connecting rods and provides parallel light. The clamping and displacement module is movably installed on one of the connecting rods, and the to-be-measured lens and the calibration plate are selectivelyplaced on the clamping and displacement module. The imaging module is fixed to one of the connecting rods, and the clamping and displacement module is located between the light source module and the imaging module, so that after the light source module is turned on, the rear focus of the to-be-measured lens and the calibration plate are imaged on the imaging module. The lens back focus measuring device is simple in structu