Taking　pyrophyllite　as　basic　raw　material,　Li5+xAl1-xZnxSi2-2xGe2xO8　(x=0.0-1.0)　lithium　fast　ionic　conductor　was　prepared　by　high　temperature　reaction.　X-ray　powder　diffraction　indicate　that　the　system　maintain　the　structure　of　Li5AlS2O8　while　x&le0.3,　and　the　structure　change　evidently　to　that　of　Li6ZnGe2O8　while　x＞0.5　IR　show　that　there　was　absorption　of　Li2CO3　while　x≥0.1,　this　indicate　that　the　Ge4+　absorb　the　CO2　from　the　air　and　the　composition　decomposed.　AC　impedance　showed　when　the　temperature　was　above　200°C,　the　synthesised　compound　possesses　a　good　conductivity　as　high　as　to　1.11×10-2　S/cm　(400°C,　x=1.0),　but　the　conductivity　was　lower　and　not　depend　on　temperature　while　x&le0.5.