Membrane separation process, which greatly meets the demand of reducing the environmental pollution in the modern industry, has become one of the most important strategies in the durative low carbon economy development.. This paper has studied the transformation structure mechanism of of Al2O3-SiO2-ZrO2 composite membrane produced by the sol-gel method on a porous α-Al2O3 support and the effects of SiO2 and ZrO2 in γ-Al2O3 membrane. Porous Al2O3-SiO2-ZrO2 composite membrane of the average pore size 2~4µm was obtained first time through controlling various factors, The structure crystal type and surface state are characterized by means of optical microscope, XRD, SEM, and IR. The results show that the membrane calcined at 1000°C obtain a composition of γ-Al2O3, t-ZrO2 and amorphous SiO2. The phase transformation has not appeared when heated at 1200°C. As the thermostability of the modified membrane being improved, the phase transformation temperature in the sintering process could be delayed. Therefore, the membranes properties are greatly improved.