The invention relates to a spring frame mechanism of equipment for detecting shell air tightness. According to the technical scheme provided by the invention, the spring frame mechanism comprises an installing seat, a bearing plate, guide blocks, a pressure lever and a baffle plate, wherein the cross sections of the guide blocks are in an L shape; the two guide blocks are fixed on the left and the right sides of the bottom of the installing seat, and are symmetrically arranged; the bearing plate is installed between the two guide blocks and compacted by the guide blocks; cushion blocks are installed between the bearing plate and the installing seat; the back side of the bearing plate is limited by the baffle plate installed on the installing seat; the front side of the bearing plate is limited by a shim installed at the front end of the guide blocks; and the pressure lever used for compacting a sealed workpiece shell is installed on the bottom of the bearing plate. The spring frame mechanism has the advantages of skillful and reasonable structure, strong compacting reliability, and flexible adjustment of compacting force; and the balance pressure lever is arranged, which facilitates to enhance the rigidity and the stability of the spring frame mechanism and ensuring simultaneous reliable sealing of each sealing point.