Abstract: In this work we have studied the phase diagrams of SDS-Water-Butanol and SDS-Water-Butanol-Heptane system. The structure of lamellar liquid crystal in both systems have studied by low angle X-ray diffraction. The result showed that the thickness of amphiphile bilayer of lamellar liquid crystal in SDS-Water-Butanol system was 2.42 nm, it did not vary with SDS/Butanol ratio. When heptane was solubilized in the lamellar liquid crystal, the solubilization caused the thickness of amphiphile bilayer to increase. While the water penetrated into the amphiphile bilayer, the thickness decreased accordingly.