L-theanine is a kind of unique amino acid green tea (Camellia sinensis) and has an important potency as a relaxtion compound. Different process on commercial green tea of Arraca Kiara and Dewata Grades enable us to get different compositions especially total solids dissolved protein and total amino acids. The objectives of this experiment are to identify L-theanine and to know green tea extract and concentrate composition through stirred cell microfilration of 0 22 um with fixed operation condition (stirring speed of 200 rpm room temperature and pressure of 30 psia) on green tea extact that processed by using steam and fanfiring. Based on optimal total amino acid recovery as L-theanine processing of green tea using steam method is better than fanfiring method and produce retentate and permeate as sources of L-theanine with concentration of total amino acud as L-theanine dissolved protein and total solids of 71 3648 and 55 041% (dry weight) 5 and 4 mg/ml and 0 4032 and 0 4548% respectively. Whereas concentrate and permeate concentration of green tea extracts using fanfiring method were total amino acid as L-theanine dissolved protein and total solids of 50 8931 and 39 8405% (dry weight) 5 and 6 mg/ml and 0 5553 and 0 7094% respectively. From chromatogram analysis for result of L-theanine via LC-MS indicated that there is no enough significant differnces on both Grades of green tea extracts.