Since the spliced sub-mirror of the primary mirror of the large-aperture telescope is off-axis aspherical, it increases the difficulty of mirror processing and inspection. In order to further improve the processing efficiency of the off-axis aspheric sub-mirror and shorten the manufacture cycle, the stressing loading method and the bluetooth-based contact two-dimensional displacement sensor array detection method and related devices are used to complete the lapping experiment on an off-axis aspheric segment with a diameter of 380 mm. First, we introduce the principle of stressed mirror processing. Then, we introduce the test method on stressing lapping and loading experimental results on the Φ380 mm glass-ceramic mirror. Second, we introduce the convergence property of the stressed grinding processing. Finally, three coordinate measuring machine and contact two-dimensional displacement sensor array are used to cross check eventually surface shape of lapped mirror. The experimental results show that the stressed grinding method is feasible and high processing efficiency.