The utility model provides a supporting shoe length measurement sieving mechanism, includes frame, conveying mechanism, detection mechanism and screening mechanism, detection mechanism is equipped with lift cylinder, parallel cylinder and contact -type displacement sensor, the lift cylinder through the support mounting at the frame top, the parallel cylinder of lift piston rod of the cylinder rigid coupling, first clamp splice, second clamp splice are connected respectively to two clamping jaws of parallel cylinder, contact -type displacement sensor is fixed with first clamp splice. The utility model discloses conveying mechanism, detection mechanism and screening mechanism be coordinated actions under control mechanism's control, can realize transport, measurement and the screening of supporting shoe voluntarily, and whole process need not artificial intervention. Detection mechanism adopts contact -type displacement sensor as detecting element, and the influence of human factor to the testing result has been avoided in the artifical measuring to the testing result accuracy. Adopt the utility model discloses reducible artifical man -hour, improve work efficiency, detecting reliability is good, can effectively avoid nonconforming product to flow in the next procedure, is favorable to improving the assembly quality of energy -absorbing box.