Alpha-fetoprotein(AFP) is the tumor marker of primary liver cancer,it is glycoprotein.An approach for quantification of alphafetoproteinby hydrolysis followed by reversed- phase liquid chromatography (RPLC)-protein cleavage-stable isotope dilution massspectrometry (PC-IDMS) is presented.The pure protein is analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS- PAGE) and hydrolysis method.The hydrolysis conditions optimized were 24h with 6mol/L HCl at 110℃.