The Codex Alimentarius Commission(hereafter CAC) is the most influential international organization for food standard. Since 1993, CAC began to discuss the issue of genetically modified food labeling, but till 2012, a widely accepted international standard has still not formed. Based on the comparision among 7 draft texts made by food labeling sub- commission of the CAC, this paper discovers that consensus on allergic labeling and no- substantial equivalence labeling is reached, but mandatory labeling for ordinary genetically modified food, threshold, exemptions and implementation are still on the debate. The difficulties for consensus on this issue are multiple. For genetically modified foods themselves, without final scientific conclusion and with big diverge on various interest groups are internal causes; and for the CAC, its close relationship with the WTO is external cause. Therefore, this paper puts forward suggestions on how to put food standard to use in GMF labeling, that is, international standard on genetically modified food labeling will be fundamental and flexible.