In this paper， the selective substrate removal technology after the silicon-based metal monolithic bonding was used. The （100） crystalline silicon was bonded to （111） crystalline silicon at high temperature by hot-pressure bonding technology. The （100） crystalline silicon substrate was protected by polydimethylsiloxane （PDMS）. Then， the （111） crystalline silicon substrate was roughened to accelerate the etching rate. Finally， the （111） crystalline silicon substrate was removed by the wet selective etching. The （111） crystalline silicon substrate of GaN epitaxial substrates was selectively removed with saving the Si-based driver chip. It is a new technology for the mixing and integration of material. It is expected to be applied in the manufacturing process of self-aligned silicon-based micro-LED microdisplay devices and optoelectronic device integration.